SlideShare a Scribd company logo
1 of 12
Download to read offline
International Journal of Trend in Scientific Research and Development (IJTSRD)
Volume 5 Issue 1, November-December 2020 Available Online: www.ijtsrd.com e-ISSN: 2456 – 6470
@ IJTSRD | Unique Paper ID – IJTSRD35908 | Volume – 5 | Issue – 1 | November-December 2020 Page 467
First Development Plan for a Small Offshore Field
Alfitouri Ibrahim Jellah
Oil & Gas Engineering Department, Bani Waleed University, Bani Walid, Libya
ABSTRACT
This work describes the proposed development program for the
accumulations in the virtual Beta field located in Libya offshore. In 2018, the
contractor informed the Management Committee about the Commercial
discovery of Beta-field. This development plan has been prepared for
submission to the Management for its consideration. After collecting all the
available data; including geological data, reservoir data, drilling data,
production data, economical data, and environmental data. The suitable
assumption has been made. All the modules were built with suitable
sensitivities. The important resultswerelaidoutwithsomerecommendations
in each section. Due consideration is paid to the environmental impact and all
the possible use is made of the existing infrastructure.
KEYWORDS: Field, Development Plan; Discovery, Oil, Reservoir Management,
Depletion
How to cite this paper: Alfitouri Ibrahim
Jellah "First Development Plan for a Small
Offshore Field"
Published in
International Journal
of Trend in Scientific
Research and
Development(ijtsrd),
ISSN: 2456-6470,
Volume-5 | Issue-1,
December 2020, pp.467-478, URL:
www.ijtsrd.com/papers/ijtsrd35908.pdf
Copyright © 2020 by author(s) and
International Journal ofTrendinScientific
Research and Development Journal. This
is an Open Access
article distributed
under the terms of
the Creative Commons Attribution
License (CC BY 4.0)
(http://creativecommons.org/licenses/by/4.0)
INTRODUCTION
Beta-field is located offshore Libya in a waterdepthof 150
m. The structure is defined as Horst and Graben fault
system predominantly orienting in the East-West
direction. The crest of this anticlinal structure is 2550 m
TVD SS with an oil water contact at 3160.5 m TVD SS. The
stratigraphy consists of an old red sandstone reservoir
from the Devonian period andsealingshale atthe topfrom
the Lower Cretaceous period. Between these two periods
lies an unconformity due to continual erosion. This
reservoir is highly fractured with low porosity and low
matrix permeability. It is composed of fluvial sediments
deposited from braided river with multi channels.
The Petrophysical analysis of the various logs from Beta-
field, show a massive column of shaly-sandstonereservoir
with low N/G, high initial water saturations and low
matrix porosities. The reservoir properties of the field
sands are poor, with porosity ranging of 10-13% and
permeability in ranges from 0.06 mD to 12 mD. The core
based wettability analyses indicate that the reservoir
sands are mixed to oil-wet.
Beta-field contains about 605 MMSTB of oil and 216.6
BSCF of associated gas in place within the massive old red
shaly-sandstone reservoir. The oil and gas that can be
economically recovered are estimated to be 157 MMSTB
and 63 BSCF, respectively. Due toits geologicalcomplexity
and associated uncertainties, it has been planned to
develop Beta-field in three phases.
A. Problem Statement
This study is to check the profitability of Beta field after
the information had been received from the contactor
about its commercial recovery.
B. Study Objectives
This study was conducted on Beta field in order to achieve
the following objectives:
Decide whether it is profitable development or not,
what are reserves and the associated uncertainty.
Figure 1 - Seismic Cross Section.
The kind of development plan should be adopted.
The way the uncertainty in the data should be
handled.
IJTSRD35908
International Journal of Trend in Scientific Research and Development (IJTSRD) @ www.ijtsrd.com eISSN: 2456-6470
@ IJTSRD | Unique Paper ID – IJTSRD35908 | Volume – 5 | Issue – 1 | November-December 2020 Page 468
Field Description
A. Structural Configuration
Beta-field was formed as a result of several geological
changes. Originally, there was an anticline, then a normal
faults system was generated, over time these started to
subside generating a Horst and Graben fault system which
created the structural trap. Subsequently on the top of the
reservoir, a stratigraphic trap was created by sealing shale
(approximate 430 ft at the thickest point). The shale was
deposited during the Low Cretaceous (140 MM years ago)
and reservoir sandstone was deposited during the Devonian
(416- 359 MM years ago) which showsan unconformity due
to the missing geological timebetweenthetworocks.Thetop
structure map shows 21 normal faults, see figure 1.
B. Fracture Analysis
Origin: The fractures were generated due to stress
during the folding of the anticlinefollowedbythenormal
faults system creating a Horst and Graben sequence, see
Figure 2.
Fracture Network: Open fractures create secondary
Figure 2 - 3D Braided River with sedimentary logs. Ref
W. Beta-9
porosity due to increase of void space, but are strongly
dependent on the scale size theyareexamined.Incertain
areas, on a small scale secondary porosity can increase
total porosity up to a factor of 100%. However, on the
reservoir scale it only increases around 1 % of the total
porosity.
Storage Capacity: Studying the matrixandpermeability
relationship, the matrix has the storage capacity and the
communicating fractures aid the permeability. This
phenomenon has been clearly demonstrated by
calculating the ratio between the permeability obtained
from the well test(K wt) andthe permeability measured
in the core (K cl).
C. Reservoir Description
GeologyThe braided riversystemconsistedofanetwork
of small channels separated by sandy or braid bars. As
there had been had a tropical desert climate and the
weather was more arid with occasional heavy rains
causing dramatically variations in channel depths,
channel velocity and sediment loads. This climate cycle
was repeated during 150 million years resulting in new
channels with low or high energy. Figure 3 shows a 3D
braided river with different sedimentary logs.
Petro physics and Reservoir Fluids The available data
for estimating the petro physical properties for include
core data and wireline logs. Table 2,lists thespecificlogs
used for the analysis of the petro physical properties. All
the exploration wells were drilled vertically except well
Beta-6. Wire line log data was available for all six
Exploration/Appraisal wells while the core data was
available from wells Beta-2,Beta-3andBeta-5.Thecores
were depth matched to the logs to ensure proper well
interpretation.
Fluid contacts The oil-water contact (OWC) was
determined from the logs by observing an average
decrease of 4 ohms in resistivity within wells Beta-1,
Beta-2 and Beta-3. From the log interpretation of these
wells the OWC was clearlyestablishedat10450ft,10490
ft and 10510ft MDBRT. The variation in the OWC has
been interpreted as a result of porosity anisotropy and
varying transition zones between the oil and water leg
and not due to compartmentalizationofthereservoir.By
selecting the shallowest OWC of 10450 ft TVD BRT, a
worst-case scenario wasconsidered.Thefreewaterlevel
(FWL) could not be established from the logs due to the
uncertainty in the transition zones. However, for the
STOIIP calculations this uncertainty has been managed
by creating three scenarios that account for the possible
FWL’s. The worst case scenario would be if the FWL was
Figure 3 – Top Structure Map with Highlighted “Known
Area”
right below the deepest known oil at 10360 ft TVD BRT,
the most likely case would have been the OWC at 10450
ft TVD BRT and finally the best case scenario wouldhave
been if the FWL was at the highest known water at
10652 ft TVD BRT.
Porosity It was obtained by comparing porosities from
the different porosity models available in Terrastation
software package. After comparing these models, the
‘Porter model’ was selected as the most representative
for porosity across the whole reservoir section. The
porosity determined from the gamma ray and sonic logs
using Porter model was compared to the manually
calculated values from the logs and the stress corrected
core porosity data, which showed good agreement
between them.
Water saturation was also determined using
Terrastation software package. Again, various models
were compared to determine the most representative
model. The ‘Laminar model’ which uses the porosity,
resistivity and V-shale from logs was then chosen as the
most representative.
Volume of shale was determined using Terrastation
software package. The various models available were
compared to determine the most representative model.
International Journal of Trend in Scientific Research and Development (IJTSRD) @ www.ijtsrd.com eISSN: 2456-6470
@ IJTSRD | Unique Paper ID – IJTSRD35908 | Volume – 5 | Issue – 1 | November-December 2020 Page 469
The ‘Density-Sonic model’ which uses the Sonic and the
Bulk Density logs was then chosen as the most
representative for the V-Shale calculations in all the
wells.
Cut off sensitivity analysis was performed on the cut
offs used for the water saturation, V-shale and porosity
in Terrastation to determine its varying effect on the net
pay thickness andselecttheoptimumvalueforeachwell.
The optimum cut off selected was the one which had the
least effect on the net pay thickness. The Cut offs were
varied by 20%, 35% and 50%of the maximumvalueand
from these an optimum cut off value for V-shale, water
saturation and porosity were selected for each well.
Porosity - Permeability Cross Plot was created for
Well-Beta-5, which had the most data available.
Reservoir FluidsThe initial drilling and testing
programmes showed that Beta-field oil is
compositionally homogeneous with similar API gravity.
PVT Study Both surface and sub-surface fluid samples
were collected in wells Beta-1, Beta-2, Beta-3andBeta-5
for testing purposes. Wellhead samples and the
recombined samples were collected at surface. Thirteen
Down hole/surface recombined samples have been
collected andanalyzed for basic blackoilPVTproperties.
The single-phase PCT sample from Beta-2 DST-7andthe
wellhead sample from Beta-2 DST-8 are considered the
most representative of the full field reservoir fluid
properties. As might be expected from the discussions
above, the PVT data also show homogeneity within the
reservoir. Ignoring these unrepresentative samples, oil
samples that are clearly representative of the main oil
column show bubblepointpressuresrangingfrom1340-
1342 psi, bubble point GOR’s of 346-359 scf/stb, bubble
point formation volume factors of 1.299 – 1.322 rb/stb,
API gravities of 31.1-32.2º, and bubble point oil
viscosities ranging from 0.83-0.86 cp.
Wettability and Relative Permeability Limited
number of special core analyses has been conducteddue
the limited time to determine capillary pressures,
wettability, oil/water relative permeability,andresidual
oil saturation. After reaching the residual oil saturation
by forced displacement, the cores were tested for
spontaneous imbibition of oil followed by measurement
of additional oil recovery by forced displacement. The
ratio of spontaneously uptake of oil tothetotaldisplaced
oil gives a wettability index to oil, OWI. The Amott-
Harvey Wettability index was calculated using the two
ratios as: WI = WWI-OWI. All the cores taken at different
depths in Well Beta-5 show a mixed oil-wet reservoir.
Initial water saturations from these cores range 8% to 23%.
Residual oil saturations from these cores range from 22% to
41%. (Figure 4).
However, there are some measurement issues with this low
permeability plug, particularly in the measurement of oil
permeabilities. Note that the end-point Oil relative
permeability is unrealistically high (kro (Swi) >1); which is
physically impossible. Hence the end point rel. perms were
modified to representcorrectdataforsimulationstudies.The
modified rel. perm is as shown in Figure 5. Further SCAL
studies would be performed on therecoveredcoredintervals
during Phase-I that is considered a valuable input before
drawing any further conclusions.
Hydrocarbons in Place
A. Deterministic STOIIP Estimates
The following scenarios have been created to try to quantify
the impact of the uncertainty with the top structure map and
the contours. Case 1 – this has been done by considering the
known area highlighted in blue in figure 6, as the most likely
P50 scenario.
In this area; the contours were then condensed by about 100
m to give P90 scenario, and extended by the same range to
create P10 scenario. Case 2 – the same three P90, P50 and
P10 GRV’s that were calculated for the knownareahavebeen
considered in this case but with the GRV of both the North
and South Flanks added on to each value.
The STOIIP estimates are highlighted in Table 4 below.
B. Uncertainty in STOIIP Estimates
The following is a list of the key uncertainties in the
estimation of STOIIP, and the work already planned which
will help to reduce these uncertainties.
Uncertainty in GRV Estimation - are due to the
uncertainty in seismic time picking of the Top and Base
horizons, position of the main bounding fault, depth
conversion of the time surfaces and Depth of the OWC.
N/G Uncertainty - The reservoir distribution inafluvial
dominated setting is always difficult to establish.
However the well control within the field has helped in
building a reservoir distribution model, which was
confirmed by the results from additional exploration
wells drilled in this area.
Hydrocarbon Saturation - The uncertainties in the
saturation estimates are mainly due to the mixed-oil wet
nature of the reservoir.
Well-5 Rel Perm - 2781.31 m (39.2 md)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
Sw (Fraction)
Kro(Fraction)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Krw(Fraction)
Kro
Krw
Well-5 Rel Perm - 2752.45 m (15.2 md)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
Sw (Fraction)
Kro(Fraction)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Krw(Fraction)
Kro
Krw
Figure 4 – Rel Perm Curves from SCAL experiments in
Well Beta-5
International Journal of Trend in Scientific Research and Development (IJTSRD) @ www.ijtsrd.com eISSN: 2456-6470
@ IJTSRD | Unique Paper ID – IJTSRD35908 | Volume – 5 | Issue – 1 | November-December 2020 Page 470
Well-5 Rel Perm - 3050 m (9 md)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
1.1
1.2
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
Sw (Fraction)
Kro(Fraction)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Krw(Fraction)
Kro
Krw
Well-5 Rel Perm - 3050 m (9 md)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
Sw (Fraction)
Kro(Fraction)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Krw(Fraction)
Kro
Krw
Figure 5 – Rel Perm & Modified Rel Perm Curves for
the most Representative Sample.
Well Performance
A. Production Test Analysis
A total of 14 drill stem tests were performed in Beta-field. In
well Beta-1 DST-3 had a mechanical failure as well DST-2 &3
in well Beta-2. The maximum oil production rate of 7492
BOPD was observed in well Beta-2 (DST-5); interval 9794-
9884 ft MDBRT & 9906-9942 ft MDBRT. The well Beta-5
(DST-1); interval 9462-9823 ft MDBRT also flowed at an
average rate of 7032 BOPD. All other wells flowed at a
significantly lower rate.
The production tests performed in three wellsBeta-1,Beta-2
and Beta-3, along various intervals were aimed to collect
most representative well test data. However due to extreme
heterogeneity along thereservoir,qualitywelltestdatacould
not be acquired. Most of the production tests show an
increase in FBHP during drawdown indicating changingskin
due to well clean up. To cope up with this uncertainty all the
well tests were screened and the most representative have
been analysed.
B. Corrosion
The corrosion level in Beta-field is intermediate, see Table
5.Hence, the use of normal materials like C80, N80 and Cr13
would be quite justifiable.
C. Wax and Asphaltenes
Currently no specific data isavailable on the wax appearance
temperature and the asphaltenes concentration of Beta-field
crude oil. A detailed analysiswould be performed in Phase–I
to highlight any possible issues arising due to presence of
wax and asphaltenes.
The Reservoir Model
A. The Geological Model
The geological modelling wasperformedmodellingdifferent
types of wells and various properties and faults. The
orthonormal system was used for selecting the origin and
the Northing and Easting of the model. The top structure
map shows a lateral extent in the X direction (Easting) of
9800 m and in Y direction (Northing) of about 7275 m. The
model was then digitized from the top structure map to
include the different contours, faults and boundaries.
Reservoir Structure -The current model isbasedon21faults
present in the top structure map which weremodelledusing
zigzag faults. These faults were constructed using vertical
pillars, which were incorporated by joiningthe midpointsof
the fault polygons in order to minimize errors associated
with verticalization.
-400.0
-300.0
-200.0
-100.0
0.0
100.0
200.0
300.0
400.0
500.0
600.0
700.0
800.0
900.0
1000.0
1100.0
1200.0
1300.0
1400.0
1500.0
1600.0
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26
Time (years)
CumNCF
Y Energy Field Cum NCF [$2008] NPV Delay NPV
Figure 6 – Illustrate NCF, NPV and they effect of delay
on NPV
B. Property Modelling
Reservoir properties have been modelled from the data
available from Terrastation as an input to Petrel. The up
scaled log data and original well log data have shown good
correlation for the basic property parameters. A mean value
of 9% for porosity, 7md for permeability and 35% for
average water saturation was obtained from both up scaled
and well logs. The well tops were identified and the OWC
was determined at 3160.5 m TVDSS.
C. Simulation Models
The static geological model was exported to ECLIPSE for
initiation of dynamic simulation. The logs show a very low
matrix permeability and porosity across thereservoirwhich
is in good agreement with the core studies. The main
objective for this full field model was to study the effects of
fracture-matrix constraints, run sensitivities and optimize
well positioning. A total of 4 producers and 2 injectors were
considered for the development of Beta field while taking
into account the various uncertainties. In all the wells
modelled a mechanical skin factor of 5 was assumed as the
best case scenario.
D. Initialization
The model has been initialised with an OWC of 10370 ft.
TVDSS. A datum pressure of 7534.7 psia at a datum depth of
9677.6 ft has been considered for hydrostatic equilibration
of liquids. The reference pressure of 7881 psia at OWC has
been used for initialization of rock and water properties.
International Journal of Trend in Scientific Research and Development (IJTSRD) @ www.ijtsrd.com eISSN: 2456-6470
@ IJTSRD | Unique Paper ID – IJTSRD35908 | Volume – 5 | Issue – 1 | November-December 2020 Page 471
E. Model Sensitivities
Natural Depletion Model - A base case with no water
leg was considered to see the effect of compaction
without an aquifer support on the recovery factor.
Initially two cases were run, with two producers
followed by two additional producers. These wells were
placed on the crestal and central location for ease of
quality data gatheringand adequate stand-offfromearly
water encroachments which proved to be optimum for
the drainage of the reservoir.
Aquifer Modelling -Theexistenceofaquiferhasalready
been determined from well testanalysisbuttheextentof
the aquifer is an uncertainty. To deal with this
uncertainty and its effect on recovery a finite numerical
aquifer was attached to the bottom of the reservoir. The
aquifer extents consideredforthismodelwere153*50m
in the X direction and 67*50 m in Y direction, extending
to thrice the size of the reservoir.
F. Main Sensitivities and Results –
Before concluding many factors had to be assessed. Out of
these a few important ones have been short listed and play
an elementary role in determining the reserves and URF of
the reservoir. The sensitivities here have beenclassifiedinto
two main categories:
1. Factors affecting STOIIP:
NTG: An increase in NTG increases the STOIIP while a
decrease automatically decreases the same. Considering
a NTG of 0.67 as our base case for matrix, two more
values has been used to run sensitivities which were
obtained from the petro physical data, see Table 6
Connate watersaturation:Fromtheanalysisoflogdata
& SCAL data no fixed connate water saturation could be
identified for Beta field. As a result a sensitivity has been
carried out for analysing the effect of connate water
saturation on the reserves, see Table 7
2. Factors affecting RF and Water cut:
Fracture Permeability: This is one of the prime and
important factors affecting the recovery andwatercutof
a reservoir. Beta-field reservoir is very heterogeneous
and has channel sandsshowingpermeabilityanisotropy.
Also, the well test data indicate different effective
permeability values at different tested intervals. The
available literature depicts that fracture porosity and
permeability are a function ofthe effective permeability.
In order to see the effects of fracture permeability onthe
reservoir different sensitivities were done, see Table 8.
Relative Permeability: Yet another important
sensitivity is the relative permeability tables governing
the relative oil and water permeabilities at different
water saturations. From the SCAL data 5 sets of relative
permeability tables were obtained. From this data, the
most representative table was chosen for the base case
while the rest were incorporated for sensitivity study.
For the results see Table 9
Faults: The top structure map and the seismic
interpretation show the presence of many faults in the
reservoir. It would be of prime importance to see the
fluid flow across these faults thatwouldhelptoknowthe
nature of faults and transportation path of fluids. This
would help in the later development stage of the field
and would help in justifying well placements. As a result
sensitivities were carried out using different values for
fault multipliers in order to see the effect on the RF &
water cut keeping 0.5 as the base case, see Table 10.
G. Recovery Mechanism
Different recovery mechanisms have been carried out using
the full field simulation model of the Beta field. Natural
depletion with and without aquifer drive has been
investigated using this model. The initial reservoir pressure
is 7881 psig at OWC which is higher than the average bubble
point pressure of 1340 psig. Hence, when producing above
the bubble point pressure, natural depletion to delineate
aquifer drive would be the most attractive and optimum
option in the first couple of years. Simulation runs indicate
that aquifer strength is a very important parameter for
deciding the further development stages, if needed.
H. Alternative Development Plans Considered
Limited data has been acquired until date from the
exploration and the appraisal wells drilled in Beta-field to
decide on a development strategy for this complex field.
Further quality data needs to be acquired in this field to
reduce the current uncertainties. Hence completing the 6
exploration/appraisal wells and acquiring the necessary
data was considered the first option to develop Beta-field.
Management Plan
A. Economic Considerations
The Economic Environment Overview Beta-field location is
in the Mid Libyan Coast in Sirt Basin. This region is generally
considered to be likely a gas area and therefore
infrastructure development has modelled this assumption.
For the purpose of this economic consideration, the
economic environment and economical strategies of Libya
will be the basis for economic assumptions and economic
feasibility analysis.
B. Cash Flow Modelling
To determine the long-term feasibility and profitability of
this project, there is a need to model the cash flow of the
project with a view of determining the base profitability
values of the project. The following base assumptions have
been made and the outcome of these assumptions forms the
input parameters of base case cash flow model.
Base Case Input Parameters
Inflation - The base price inflation for the cash flow
model is 2.5%. This is based on the forecasted Libyan
inflation rate 2.5%.
Oil and Gas Price - The base assumption for oil and gas
price are shown below:
OIL
PRICE
Oil price assumption in nominal terms is us
$88.25/barrel in 2018, $72.13/barrel in
2019, $68.29/barrel in 2020, $64.61/barrel
in 2011 escalating at 2.5% per annum from
the beginning of 2022 onwards.
GAS
PRICE
Gas prices are linked to oil prices with a lag of
three months. the average annualised gas
price in nominal terms is $10.42/mcf in 2018,
$9.45/mcf in 2019, $8.63/mcf in 2020,
$8.19/mcf in 2021, escalating at 2.5% per
annum from the beginning of 2022 onwards
A discount of 10% has been assumed based on the fact that
the API of Beta Field (320).
International Journal of Trend in Scientific Research and Development (IJTSRD) @ www.ijtsrd.com eISSN: 2456-6470
@ IJTSRD | Unique Paper ID – IJTSRD35908 | Volume – 5 | Issue – 1 | November-December 2020 Page 472
Production Profile - The base case production profile
for this economic model is the result of the full field
simulation model run on eclipse. However to determine
the economic life of the field, a plot of the revenue and
operating cost / expense with time was done and it was
determinedthattheoperatingcost(2018realterms)will
become higher than the revenue (2018realterms)inthe
23rd year.
Opex and Tariff - The components oftheOperatingCost
include; Annual lease cost for FPSO, Gas pipeline usage
tariff and CO2 and NOx tax. The base assumption for the
lease cost is based on the average of the FPSO lease cost
for field with similar production rates and recoverable
reserves. The tariff for the transport system used in the
base case cash flow model is (NKr 2.0 – 2.2 per Mcf). The
CO2 andNOx tax is also considered asanoperatingcostin
this base case model.
Capex - The Capex of a development project is
dependent on the following factors: Location
peculiarities(remoteness,waterdepthandavailabilityof
infrastructure), Reservoir geology and complexity, fluid
properties (viscosity, numberofphases,impurities).The
following development approaches were considered:
1. Lease FPSO, lay 30 km gas pipeline to the existing
transport system for gas transport, Rent drilling rig
for drilling operations and oil sales Free on Board
(FOB).
2. Build FPSO, lay 30 km gas pipeline to the existing
transport system for gas transport, Rent drilling rig
for drilling operations and oil sales Free on Board
(FOB).
3. rig for drilling operations and oil sales Free on
Board (FOB).
4. Build Semi Sub for production processing, FSU for
storage and lay 30 km pipeline to the existing
transport system for gas transport, Rent drilling rig
for drilling operations and oil sales Free on Board
(FOB).
Tax - The base case considered for taxation is same as
described in the economic environmentanalysissection.
Discount Rate - The discountrateemployedforthebase
case is based on the mostlikelycasediscountrate(10%).
Base Case Cash Flow Model
Maximum Capital Outlay (MCO)– Inthiscase,theMCO
for the base case model is USD210.3 million. MCO is the
minimum point on the cumulative cash flow and it
indicates the maximum amount of money to be sourced
external to the project if the project is to survive the
investment phase. It should also be noted that it is not
same as the maximum Capex.
Capex – For this project will be USD518million.Capexis
alsoa measure of investmentsizeandgivesanindication
of the cost of creating a productive unit. In this case it
does not end before production as investment continues
even after production has started.
Pay Back – the Payback for Beta-field base case is 2.5
years. The payback is a measure of how long before
investments are recouped.
Terminal Cash Surplus (TCS) – For the base case is
USD1428 million. It is an indication of the profit to be
made by the project beforetakingintoaccountthecostof
capital and the risk elementsof theinvestment(discount
rate).
Profit to Investment Ratio (PIR) – For the base case is
6.7.
Internal Rate of Return (IRR) – For the base case is
86.5%.
NPV – The NPV for the base case is USD 705Million. The
NPV calculated for the base case is based on 10%
discount rate.
NPVI - The NPVI for the base case is 3.5 and the MCO
Index is 6.8.
Development Plan
Beta-field oil has no unusual or troublesome properties,
especially for water flooding. Beta-field’s high initial
reservoir pressure 7881 psig at OWC, low GOR 358SCF/STB
and low bubble point pressure 1340 psig, means that
pressure maintenance by water flood might not be very
critical at initial stages for reasonable recovery levels.There
is sufficient evidence for these fractures being cemented,
close to the OWC and within the water leg asdiscussedinthe
sections above. Beta-field would be developed in different
phases. The three Phases of development would be as
follows:
A. Phase-I: Natural depletion with 2 producers for initial 4
years.
B. Phase-II: Natural depletion and/or Water-Flooding with
3 additional producers and 3 injectors depending of
success of Phase-I.
C. Phase-III: Use of gas lift for increasing ultimaterecovery
and economic water cut.
Well Optimization
From the production profiles and the simulation studies
done, an estimate of well optimization was established.
Differences in recovery factors along with increase of wells
and increase in water cut were plotted in order to optimize
the number of wells to be used for the development.
A. Base Case Development Plan
Initially in Phase I, a naturaldepletionmechanismwas
adopted. Two deviated wells acting as producers were
placed on the crest and drilled into the northern and the
southern flanks. The reason for the same was the
presence of vertical and high angular fractures in the
reservoir which constitutethemainfluidflowpathways.
Two sensitivities, with and without aquifer were
modelled to see the effect on RF.
Case 1 : 2 producers with NTG = 0.67,Faulttransmissibility
= 0.5, Skin = 5, BHP = 1500 psia (well control),
without aquifer and runtime of 25 years. See Table
12.
Case 2 : 2 producers with NTG = 0.67,Faulttransmissibility
= 0.5, Skin = 5, BHP = 1500 psia (well control), with
aquifer and runtime of 25 years. See Table 13.
Wells Drilling and Work over
For Beta-Field development; it is recommended to use a
second generation Semi-submersible so cost will be lower.
It’s is capable of drilling in water depths of 1000 ft and can
drill up to 25000 ft which is well within the expecteddrilling
targets. The phased drillingprogrammeisplannedthrougha
drill centre with six slots on the seabed having a spacing of
15m between them. The FPSO will be located in such a
position to accommodateanyunplannedwork overswithout
interrupting the production.
International Journal of Trend in Scientific Research and Development (IJTSRD) @ www.ijtsrd.com eISSN: 2456-6470
@ IJTSRD | Unique Paper ID – IJTSRD35908 | Volume – 5 | Issue – 1 | November-December 2020 Page 473
A. Pore & Fracture Pressure Prediction
It is assumed the formation above the reservoir is normally
pressured with a pressure gradient of 0.453 psi/ft. An oil
gradient of 0.35 psi/ft is expectedwithinthereservoir which
is over pressured by 2300 psi. For the normally pressured
zone; an overbalance of 150 psi will be maintained while for
the reservoir section it has been decided to maintain an
overbalance of 100 psi to minimize formation damage
(figure 7).
B. Deviation Design
It has been planned to follow a deviated well path with an
angle of 55° to intersect the maximum number of high
angled / vertical fractures and the inter-bedding layers
within the reservoir, while keeping the angle within the
range of wire line services. See figure 8.
Figure 7 - Pore Pressure Profile
A Positive Displacement Motor onthe17-1/2”PDCsteerable
motor assembly will be used to kick off at 6250 ft with a
build up rate of 1.5° / 100 ft to have a 10° angle at the 13-
3/8th casing setting depth (6490 ft) with an azimuth of 180°.
The initial 10° angle is to reduce the severity of the build
angle in the subsequent hole section. At the kick offpointthe
formation is consolidatedsandstonewhichisnotexpectedto
be a troublesome formation. Most essentially, the 10°
inclination would facilitate the 12-1/4” rotary steerable
system in finding the high side of the hole.
The 12-1/4” RSS will be used to build up to 55° at BUR of 2°
/ 100 ft drilled with an azimuth of 180° to a TD of around
9320 ft. The TD for the 12-1/4” section would dependonthe
rate of pressure increase in the transition zone (shale
section), which would be monitored using the MWD to
indicate the over pressured zone.
C. Litho logy
The compositional logs were analysed carefully and the
expected litho logy description was used in choosing the
casing setting depths.
D. Drilling Schedule
Drilling objectives of Phase I:
Establish the reservoir potential of Beta-field by
entering the Southern & Northern Flanks.
Core reservoir section
Complete suite of open hole logs
E. Drill bit Selection
Spud Drilling (9890 ft MD BRT) – While drilling
thissection a one-trip approach will be implemented
using a 17 ½” / 36” hole-opener. Once the TD for this
section is reached the boulder intervals would be wiped
clean to check for ledgesandensurethattheconductoris
run within <1° inclination.
26” Drilling (2663 ft MD BRT) - This interval will be
drilled with a 26” Roller Cone drill bit studded with
tungsten carbide insertcutters. This is consideredbased
on the length of this hole section (1673 ft), the cost of
this type of bit (lower) and no hole size constraints. The
drill string is designed to accommodate a small offset
angle as to facilitate scrapping action and increase the
drilling rate in the softer formations
17-1/2” Drilling (6595 ft MD BRT) - This interval will
be drilled with a 17-1/2” PDC steerable motor assembly
(SMA). The PDC has been selected due to its extended
drillinglife (no moving components)anditissuitablefor
drilling in hard, non –sticky formations without bit
balling. The SMA will be in a rotary mode until it drills
vertically up to 6100ft. It will then be switched to its
sliding mode withcontinuous mud circulation througha
PDM driving the drillbit.
Figure 8 – Deviated Well Profile
12-1/4” Drilling (8853 ft MD BRT) - This interval will
be drilled with a PDC Rotary Steerable System. The PDC
bit is selected to achieve longer drilled intervals,
lowering the amount of trip time and reducing the
chances of failure due to no moving components. It also
gives proper hole cleaning benefits allowing rotation of
the string while building up at 2°/100ft up towards 55°.
8-1/2” Drilling (12186 ft MD BRT) - This interval will
again be drilled with a PDC Rotary Steerable System for
the same reasons as discussed in the previous section.
However, the most important selection criteria for RSS
for this hole section was to allow flexibility in
maintaining correct path and deviation to reach the
target zone in the Southern Flank.
F. Casing Design
The current calculation for the burst and collapse loads are
based on the fluid properties that are present in the
reservoir (discussed in reservoirengineering)andthefuture
possibility of gas lifting, see table 14. However if phasethree
is delayed then a possible work over and a re-evaluation of
the casing integrity would be expected.
International Journal of Trend in Scientific Research and Development (IJTSRD) @ www.ijtsrd.com eISSN: 2456-6470
@ IJTSRD | Unique Paper ID – IJTSRD35908 | Volume – 5 | Issue – 1 | November-December 2020 Page 474
Run and Cement 30” Casing (984 ft MD BRT) - This
procedure could have problems getting conductor to
bottom due to bottom fill and/or boulders falling /
protruding into the hole. The drill pipe stringer would
help on reducing the pumping time with lower
displacement volumes and no chance of packers
becoming stuck. However, “bridging off” in the annulus
space might be an issue as large compressive loads may
cause the conductor to collapse. The Top of Cement
(TOC) will be to the seabedbetweenthetemporaryguide
base (TGB) and permanent guide base (PGB). An excess
of 100% of the gauge hole annular volume is planned to
ensure good returns to seabed since this is a major load
bearing element in the wellhead system.
Run and Cement 20” Casing (2658 ft MD BRT)- The
20” surface casing will be cemented using single stage
method as low pump pressures are expected at this
shallow depth. The TOC will be till seabed between the
TGB and PGB since this casing cement bond willalsobea
major load bearing element in the wellhead system. The
casing setting depth has been chosen to have the casing
shoe within the limestone section and ensure a good
L.O.T for the 17 1/2” section.
Run and Cement 13-3/8” Casing (6590 ft MD BRT) -
The 13-3/8” intermediate casing will again be cemented
usinga single staged cementing operation. The available
data shows no lost circulation within this section. The
TOC is planned 500 ft above the 13-3/8 casing shoe at
6068 ft. The TOC will be changed to isolatethezonesthat
contain gas lostcirculation zones. The amountofcement
required for a particular job wouldbeonlydependenton
the drilling problems encountered while drilling the
section.
Run and Cement 9-5/8” Casing (8848 ft MD BRT) -
The casing setting depth for this 9-5/8” production
casing is in the shale region just before the over
pressured reservoir is encountered.Thiswouldfacilitate
change over to higher mud weights before entering the
over pressured reservoir. From analysis of the mud logs
a lost circulation zone is likely to be encountered in the
limestone region around 7300 ft would alsobesealedoff
behind the casing. The top of cement for this casing
interval will be placed 500ft above the expected lost
circulation zone using a two staged cementing method.
G. Well Control
The BOP stack will be installed after cementing the 20”
surface casing. The further hole sections would be drilled
with a 10 000 psi BOP in place. The rating of the BOP stack is
chosen on the basis of a worst case scenario of gas filling the
casing all the way to surface. This scenario gives the
expected surface pressure of 6150 psi which even with a
safety factor of 20% is covered by the BOP rating. Once the
10, 000psi BOP is latched on it will be pressure tested to its
working pressure limit before drilling later hole sections.
The 26” hole will be drilled without a riser to around 2658 ft
TVD BRT. From the available data the risk of encountering
shallow gas has been deemed to be ‘low’. However, shallow
seismic data, tidal current data with respect to tidal position
and possible gas cone degree size will have to be collected
before this decision is finalised.
If loses are seen while drilling the mud weightshouldfirst be
cut back to stop losing excessive mud in the fractured
formation. If heavy losses continue, which is expecteddueto
fractures or faults being “re-activated”and/oropeningin the
formation then heavy duty LCM pills should be added.
H. Drilling Mud Design
It has been intended to use seawater planned until placing
the riser and BOP to minimise environmental impact. Then
moving to a water based mud with KCl / polymer to drill
down to the setting depth of the 9-5/8” casing, to avoid any
instability problems. Losses are expected when drilling the
8-1/2” hole section within the fractured. From the past data
in well Betta-2 a maximum mud loss of 49 bbl/hr had been
documented. Even though the high loss rates were not
encountered while drilling the previous wells in Beta-field,
safety measures should be in place to deal with these
situations.
Casing and Completion Design
1. Completion design
An openhole Subsea completion is plannedforthe newwells
in Phase-I and II, as the reservoir is naturally fractured, well
consolidated with a very low matrix porosity and
permeability. The Subsea completion is designed to include
all the necessary completion jewellery like TRSSSV, gas lift
mandrels, telescopic joint, SSD, Hydraulic set permanent
packer with seal receptacle, top and bottom no-go nipples
and a wireline entry guide. The 4-1/2” completion string
would be RIH as an integrated assembly to set the Hydraulic
packer as deep as possible and to have the WEG just below
the 9-5/8” casing shoe depth. This wouldleavea complete 8-
1/2” openhole section across the reservoir. This is planned
to have the highest Kh and the maximum inflow area
available for flow. Though the formation is quite
consolidated, the tendency for sand production in the later
life of this field after water breakthrough cannot be
neglected. Due to lack of sieve analysis data, a detailed sand
control design could not be achieved at this stage.
The various Completion equipment are:
Tubular: The tubing sizes considered for different
sensitivities were 2-7/8”OD, 3-1/2” OD, 4” OD, 4-1/2”
OD, 5” OD and 5-1/2” OD. The criterion used toselectthe
optimum tubing size was based on the technical and
economic considerations. A reservoir pressure of
5500psi with a FTHP of 1000 psi and a maximum
expected skin of 15 with a variation in water cut from 0-
90% was considered the worst case scenario for this
analysis.
It can be seen from this analysis that increment in oil
flow rate by increasing the tubing size from 4-1/2” to 5”
is small as compared to the increment from 4” to 4-1/2”
tubing.
Down hole Safety Valve: A Tubing Retrievable Sub-
Surface Safety control Valve (TRSSSV) which provides
more advantages compared to the Wire line Retrievable
Safety Valve will be used. A TRSSVismorereliableasthis
leaves less chance of control system leaks, permits a full
bore passage and reduces wire line interventions. A
flapper-type valve will also be required for a temporary
lock-out.
Production packer: A 9-5/8” hydraulic set permanent
packer with seal receptacles will be used. This packer
will be run on the completion tubing.
Gas lift Mandrels: 3 x4-1/2” gas lift mandrels would be
run along with the planned completion for future
possible gas lifting operations.
International Journal of Trend in Scientific Research and Development (IJTSRD) @ www.ijtsrd.com eISSN: 2456-6470
@ IJTSRD | Unique Paper ID – IJTSRD35908 | Volume – 5 | Issue – 1 | November-December 2020 Page 475
SSD: A sliding side door is included in the completionfor
well killing operations for any possible workovers.
Telescopic Joint: This equipment isrequiredasapartof
the tubing to accommodate any expansion that will take
place during production.
Wire line entry guide: is used for smooth wire line
interventions without any hung-up.
Swell packer: This is a special type of packer which is
used as an open hole plug to reduce the water cut. This
will be required to plug off the watered out open hole
sections in future.
Tubing Hanger: The type of tubing hanger used is the
hydraulic type which provided the facilities for tubing
hanger setting and simultaneous wire line access to the
bore.
Subsea Xmas Tree: The production from the well
required a Xmas Tree with a 4-inch nominal bore. The
main valve assembly comprises of lower manual master
valve, upper master valve, hydraulic wing valve and
swab valve. These valves are fixed on the downstream
side then connected to theflowloop.Thepressurerateof
the wellhead equipment is 10000 psi.
Production Facilities
The potential production facilities available for the
development include:
A. Floating Production, Storage Facility
From the economic and technical benefits,a FPSOunitwould
be leased for this development. This unit which has a mono
hull construction type will be considered becauseitwill host
all the necessary facilities including the production,
processing, storage and export. The FPSO will be placed
between the glory holes and will receive productionvia flow
lines through the turret located near the bow of the vessel.
B. Surface Facilities for Production and Storage
Vessel - The FPSO will have a design life of 25 years with
a storage capacity of roughly 500000 barrels
representing about 7 to 9 days of production. The peak
liquid production to be handled by this FPSO will be
45000 barrels of oil per day and 13000 barrels of water
per day.
Test Separator - will be used for carrying out periodic
well test to collect reservoir data.
Multi-Stage Separator - The first stage separator (HP
separator) will provide the initial stage of the crude oil
separation. The incoming production fluids will be
heated and allowed to settle in the HP separator. Crude
from the first separator will be further separated in the
LP separator and then in the electrostatic treater. Here
remaining gas and water will be removed from the oil.
The sales quality oil thus produced will then flow to the
cargo tanks for storage until offloading. Water that has
been separated from the oil will be processed to remove
dissolved gasses.
Gas Compressors -SeparatedgasfromtheHPseparator
will be compressed to high pressure to allow it to be
injected at the subsea wellhead soastofacilitatetheflow
of the incoming production fluids(gaslift)laterinthelife
of the field.
Water Treatment - The produced water will then be
treated to meet a maximum concentration of 30mg/l of
oil-in-water specification before it can be disposed
overboard.
Utility Systems – Three main utility services will be
needed – heating,coolingandelectricity.Theheatingand
cooling will be providedbytheamedium,whichcontains
circulating hot fresh water for process heating and cold
fresh water for process and compressor cooling. The
heating for the hot water system will be achieved using
steam from the vessel’s boilers, and cooling for the cold
water system will be achieved by using seawater.
Seawater lift and injection system - During Phase-II,
sea water will be required for injectionintothereservoir
for pressure maintenance. Thus, three lift pumps and
coarse filters will be required to treattheseawatertothe
reservoir filtration requirements. De-aeration of the
seawater will also be carried out prior to injection to
prevent corrosion in the injection well.
Gas Generators - Three Gas generators will provide
electric power for the FPSO. Under normal conditions,
two of the three topsides High Voltage (HV) generators
will be on line. These will supply all topsides and vessel
consumers.
Flare and Vent System - There will be no continuous
flaring except during emergency conditions. Measures
will be evaluated to reduce atmospheric emission
wherever possible.
Safety Equipment - The vessel will be provided with a
minimum of 150 percent capacity in persons onboardin
lifeboats and 200 percent capacity in life rafts. Lifeboats
and life rafts will be located close to the temporary
refuge and on both sides of the vessel. Additional
lifeboat(s) and life rafts will beprovidedatothersuitable
locations on the vessel. All safety equipment will meet
international marine requirements.
Accommodation - The FPSO will provide
accommodation for about 50 to 60 people located
furthest away from the skids containing oil and gas.
Crude Oil Metering - The crude oil product will be
metered to custody transfer standards before offloading
to the off-take tankers. Quantity and quality
measurement of the liquid will be required to satisfy the
DTI legal requirements for accounting and reporting
purposes
Export Gas Metering - Prior to being exported to the
transportation system, dry associated gas will be
metered by an orifice plate meter to the fiscal standard.
Also, the quality of the gas will be compatible with the
dense phase flowing criteria.
Injection - Venturi flow meters will be installed on the
Xmas tree to monitor the injection volumes.
C. Subsea Production and Associated Facilities
Subsea trees and controls - Subsea Christmas trees
employed shall either be of vertical or horizontal
Christmas tree and these will be using the
manufacturers’ specifications. It will have the capability
for production with gas lift and water injection.
Subsea manifolds modules - Manifold modules will be
required to handle flow from the producing wells and
direct them into the production flow line headers,
pigging loops, flow meters and control systems. Subsea
manifolds will also be required for Phase-II of this
development plan. This will provide for the functions of
water injection and control.
Subsea control systems and umbilicals - The Subsea
control system is expected to be an open loop system
that is powered electro -hydraulically. The FPSO located
control equipment will be connected to the subsea
International Journal of Trend in Scientific Research and Development (IJTSRD) @ www.ijtsrd.com eISSN: 2456-6470
@ IJTSRD | Unique Paper ID – IJTSRD35908 | Volume – 5 | Issue – 1 | November-December 2020 Page 476
equipment (e.g. manifold) via electro-hydraulic control
umbilicals. Dynamic umbilicals will be used for control
from a FPSO. The control system will be designed to
supply sufficient hydraulic fluid high pressure (HP) and
low pressure (LP) to control the remotely operated
valves on the manifolds and Christmas trees at all drill
centers. Consideration will also be given to possible
future expansion requirements.
Subsea flow lines and risers - The flow lines and risers
for Beta-field will be designed to the APIstandards.They
will provide an unobstructed flow conduit between the
subsea facilities and the FPSO and will be fully
compatible with the intended service for the entire
design life. Valves will be installed to control flows for
both normal and emergencysituations. Design wise, it is
expected that no maintenance will be required during
the design life, except for external inspection using an
ROV and damage repair and operational pigging.
D. Production Export Systems
Offloading facilities - The FPSO will be designed such
that the offloading facilities will be located at the sternof
the vessel. A fiscal metering system will be incorporated
as an integrated package.
Oil export - Crude oil will be exported directly from the
FPSO to the shuttle tanker. The shuttle tanker will be
expected to be in the size range of 80,000 DWT. The
cargo storage capacity is expected to be around 480,000
bbls to meet peak productionstorageperiodofupto8-10
days.
Gas Export -Process gas export will be achieved via a
nominal 6” diameter pipeline from the FPSO to the 42”
Transport pipeline. This pipeline will be expected to be
about 30km in length and will be trenched. The
Transport pipeline will run some 730km to the landfall
site at Karsto.
Environmental Impact
A. Existing Environment
The measured sensitivities of the area are described below.
1. Any of this area has not been designated as a Special
Areas of Conservation (SAC)ora Special ProtectionArea
(SPC). The bottom sediment within this area is mainly
mud and sand.
2. Seabirds are present throughout the year in this area
except in April, September and December.
3. The fishing effort is classified as relatively low in this
part of Libyan water.
B. Risks and modification plans
Modification plans have been developed for some activities
which may cause environment impacts. The measured
environmental impacts are described below:
1. High or low frequency sound emit into the marine
environment during anchoring the drillingrigandwhile
drilling.
2. The emissions raised from the drilling and production
operations mainly from burning of well oil and gas
during the short term of drill stream test and diesel
combustion for power generation.
3. Oil spills and leaks may occur during various stages of
the field development activities.
4. The seabed would directly be disturbed from the
placement and the subsequent dragging of rig anchors.
But, the physical presence of anchors is expected to
create minor environmental impact on the benthos,
which should recover quickly once operations are
completed.
5. The cuttings contaminated from oil will be contained
and shipped to shore for reprocessing at a licensed site.
Abandonment
A. General
The current economicproductionfromBeta-fieldisexpected
to last 25 years. However, this might extend depending on
the success of Phase-II and Phase-III. Decommissioning of
the wells and facilities will be in accordance with the legal
requirements on the disposal of disused offshore
installation.
B. Subsea facilities
It is planned that even though the sizes of all sub-sea
pipelines are less than 10”, all those lines in trenching and
burial will be flushed,pluggedanddecommissionedin-place.
C. Wells
To achieve effective isolation of the reservoir; all wells will
be plugged and abandoned with two permanent barriers
from the seabed and casing string will be recovered.
D. FPSO
The leased FPSO of Beta-field will be disconnected from the
risers and collected by the leasing company. Any residual
hazardous waste arising from this will be taken to shoreand
treated at appropriate approved waste treatment facilities.
Costs
A. General
The cost implications for this development plan have been
divided into 2 broad aspects.
1. Capital Expenditure (Capex)
2. Operating Expenditure
A breakdown of the revenue and the project costs including
Opex, Capex and taxes is illustrated in figure 9.
B. Exploration, Appraisal and Development Costs
The key components of the Capex include the drilling, sub
sea completion and the 30km pipeline from the FPSO to the
transport system. There is no exploration and appraisal cost
covered in this report as these cost have been considered as
sunk cost. Due to the marginal nature of this field and the
significant level of data uncertainty, the Capital expenditure
will be phased into the three distinct phases.
A pie chart that shows the phases and the magnitude of
expense is shown below.
C. Operating Expenditure (Opex)
The Opex for this project can be considered high as this
includes the cost of leasing the FPSO facility. Other
components of the Opex include well maintenance,
insurance logistics and consumables. Pipeline usage tariff is
also included in the Opex.
D. Abandonment Cost
The abandonment cost for this project would cost $53.9
million in 2018 terms. This value comprises the cost of
plugging the 4 producers and the 2 injectors. It will also
include the cost of abandoning the pipelines. The FPSO
International Journal of Trend in Scientific Research and Development (IJTSRD) @ www.ijtsrd.com eISSN: 2456-6470
@ IJTSRD | Unique Paper ID – IJTSRD35908 | Volume – 5 | Issue – 1 | November-December 2020 Page 477
lease contract will be terminated. The leasor will be
responsible for its abandonment.
Opex
Capex
Tax
NCF
Opex Capex Tax NCF
Figure 9 – NCF as a proportion of the revenue.
Abandonment
Phase 3
Phase 2
Phase 1
Abandonment Phase 3 Phase 2 Phase 1
Figure 10 - Distribution of the Capex over the life of the
project
Operating personnel
Logistics and
consumables
Inspection and
maintenance
Wells Insurance
Tariff costs
Lease
Operating personnel Inspection and maintenance Logistics and consumables
Wells Insurance Tariff costs
Lease
Figure 11 – Showing the distribution of the Opex over
the life of the project
References:
[1] Reynolds D, (2006), 'High Performance Water Based
drilling fluid helps achieve early oil withlowercapital
expenditure' SPE 96798
[2] Svein Fantoft, (1992), 'Reservoir management of the
Oseberg field After four years productionhistory'SPE
25008
[3] Morton K, (2006), ‘’Selection and Evaluation criteria
for High Performance drilling fluids’' SPE 96342
[4] Chaudhry, A.U; (2004), “Oil Well Testing Handbook”;
USA; Elsevier;
[5] Jellah, A. I. et al., (2016), “Water Injection
Performance Calculations in Intisar 103A Oil Field,
Libya” , Paper presented at ICCPGE conference, Al-
mergib University, Libya, ,
[6] Dye William et al, (2005), ‘New Water-Based Mud
Balances High Performance Drilling and
Environmental Compliance’ SPE 92367
[7] Dawber M et al, (2005), ‘Moving from Wire-line
Logging to Logging-While-Drilling in an Aggressive
North Sea Drilling and Formation Evaluation
Program-A Case Study of the Brenda Accumulation’
SPE 96716
[8] Du K. E, Pai S. (2005), ‘Optimising the development of
Blake field under tough economic and environmental
conditions’ , SPE64714
[9] Blikra H, Andersen R, (2002), ‘Cost-effective Subsea
drilling operation on the smallest Norwegian field
development’ , SPE 74508
[10] Lanquentin B. ‘More Than 30 Years Experience with
FPSO’s and offloading techniques’ 2005 IPTC 10901
[11] Stenger BA. (2006), ‘Extracting value from a dormant
small offshore oil field: The Okwori Field Case’ , SPE
98875
[12] Maclean A. ‘Enhancing marginal Field Development
economics by leasing operated production facilities.
2005 SPE 93507
[13] Stephen KD ‘Modelling and flow simulations of a
north sea turbidite reservoir: Sensitivities and
Upscaling’ 2002 SPE 78292
[14] Page Paul, Chris Greaves ‘Options for the recycling of
drill cuttings’ 2003 SPE 80583
[15] Toole ST, Grist DM ‘Oil & Gas recovery behaviour in
the UKCS basins’ 2003 SPE 83982
[16] Morton K., Bomar B, (2005), ‘Selectionand evaluation
criteria for high-performance drilling fluids’ , SPE
96342.
[17] . Holder Barry, J. et al, (1980 ), ‘Drilling Fluids for
Highly Deviated Wells in North Sea Petroleum
Drilling’ SPE 10860
[18] Hauge R et al, (2003), ‘Modeling Facies Bodies and
Petro-physical Trents in Turbidite Reservoirs’ SPE
840
[19] Alyan, M., Martin, J., & Irwin, D. (2015, November 9).
Field Development Plan Optimization for Tight
Carbonate Reservoirs. Society of Petroleum
Engineers. doi:10.2118/177695-MS
[20] Safran, E. M., & Al Ansari, S. I. (2020, May 4). Flow
Assurance Risks Impact on Kuwait Offshore Field
Development Plans. Offshore TechnologyConference.
doi:10.4043/30851-MS
[21] Abdalla, O. S., Shawky, M., Badawy, O., Maarouf, M., &
kamal, Y. (2015, September 14).ContinuesUpdatefor
PetroSilah Full Fields Development Plan Results of
Production and Reserves. Society of Petroleum
Engineers. doi:10.2118/175807-MS
[22] Teh, Y. H., Theseira, K., Abdul Karim, A. H., Hashim, N.
S., Yakob, A. R., Musa, A. S., … Sykahar, M. W. (2008,
January 1). Preparing a Gas Field Development Plan :
Tangga Barat Cluster Gas Project. International
Petroleum Technology Conference.
doi:10.2523/IPTC-12488-MS
[23] Ojeke, A., Itotoi, I. H., Nnamdi, D., Umurhohwo, J., &
Benjamin, O. (2011, January 1). A Robust Approachto
Field Development Plan Integrating Multi dynamic
Reservoir Models with Surface Network. Society of
Petroleum Engineers. doi:10.2118/150735-MS
[24] Tahir, S., Al Kindi, S., Ghorayeb, K., Haryanto, E., Shah,
A. R., Yersaiyn, S. … Ali, S. (2019, November11).ATop
- Down View of Field Development Plans, Integrated
International Journal of Trend in Scientific Research and Development (IJTSRD) @ www.ijtsrd.com eISSN: 2456-6470
@ IJTSRD | Unique Paper ID – IJTSRD35908 | Volume – 5 | Issue – 1 | November-December 2020 Page 478
Reservoir Performance and ProductionSustainability
Assurance. Society of Petroleum Engineers.
doi:10.2118/197379-MS
[25] Sierra, F., Monge, A., Leon, S., Vasquez, F., Garcia, J.,
Llerena, G., & Borjas, J. (2015, November 18). A Real
Case Study: Field Development Plan Evaluations for
Oso Field. Society of Petroleum Engineers.
doi:10.2118/177071-MS
[26] Vilela, M. J., Marin, P. R., Rodrigo, M., Medina, A.,
Limeres, A. C., & Mata Petit, F. E. (2007, January 1).
Building The Field Development Plan For A New Gas
Field, Located In Algeria, Reggane Trend. Society of
Petroleum Engineers. doi:10.2118/108831-MS
[27] Denney, D. (2011, October 1). Offshore-Field
Development Plan Changed From Steel Structures to
Artificial Islands. Society of Petroleum Engineers.
doi:10.2118/1011-0065-JPT
[28] Kasap, E., Sanza, G. J., Ali, M. I., Friedel, T., Waheed, A.,
Sukmana, A. Y. … Rasol, M. N. (2006, January 1). Field
Development Plan by Optioneering Process Sensitive
to Reservoir and Operational Constraints and
Uncertainties. Society of Petroleum Engineers.
doi:10.2118/101556-MS

More Related Content

What's hot

Geotechnical Engineering-I [Lec #8: Hydrometer Analysis]
Geotechnical Engineering-I [Lec #8: Hydrometer Analysis]Geotechnical Engineering-I [Lec #8: Hydrometer Analysis]
Geotechnical Engineering-I [Lec #8: Hydrometer Analysis]Muhammad Irfan
 
Study Results: Delineating Injection Well Buffer Zones in Brackish Aquifers
Study Results: Delineating Injection Well Buffer Zones in Brackish AquifersStudy Results: Delineating Injection Well Buffer Zones in Brackish Aquifers
Study Results: Delineating Injection Well Buffer Zones in Brackish AquifersTexas Alliance of Groundwater Districts
 
IRJET- Open Channel Flow Characteristics using Gabion Weir
IRJET- Open Channel Flow Characteristics using Gabion WeirIRJET- Open Channel Flow Characteristics using Gabion Weir
IRJET- Open Channel Flow Characteristics using Gabion WeirIRJET Journal
 
Potential impacts of CO2 storage on groundwater resources
Potential impacts of CO2 storage on groundwater resourcesPotential impacts of CO2 storage on groundwater resources
Potential impacts of CO2 storage on groundwater resourcesGlobal CCS Institute
 
Exploration for unconventional gas in russia
Exploration for unconventional gas in russiaExploration for unconventional gas in russia
Exploration for unconventional gas in russiaHtet Naing Htoo
 
Bodem Breed 2011 - Potential of Aquifer Storage and Recovery (ASR) for a clim...
Bodem Breed 2011 - Potential of Aquifer Storage and Recovery (ASR) for a clim...Bodem Breed 2011 - Potential of Aquifer Storage and Recovery (ASR) for a clim...
Bodem Breed 2011 - Potential of Aquifer Storage and Recovery (ASR) for a clim...Koen_Zuurbier
 
Hydrodynamic Modeling of the Physical Dispersion of Radium-Enriched Barite Ai...
Hydrodynamic Modeling of the Physical Dispersion of Radium-Enriched Barite Ai...Hydrodynamic Modeling of the Physical Dispersion of Radium-Enriched Barite Ai...
Hydrodynamic Modeling of the Physical Dispersion of Radium-Enriched Barite Ai...Donald Carpenter
 
Rationalizing the 1962-2006 Drop in Water Levels of Lakes Michigan and Huron
Rationalizing the 1962-2006 Drop in Water Levels of Lakes Michigan and HuronRationalizing the 1962-2006 Drop in Water Levels of Lakes Michigan and Huron
Rationalizing the 1962-2006 Drop in Water Levels of Lakes Michigan and HuronMoin Syed
 
Petrophysical Properties of Reservoirs and Seal Characteristics at Ataga Oil ...
Petrophysical Properties of Reservoirs and Seal Characteristics at Ataga Oil ...Petrophysical Properties of Reservoirs and Seal Characteristics at Ataga Oil ...
Petrophysical Properties of Reservoirs and Seal Characteristics at Ataga Oil ...IJSRED
 
IRJET- Parameters Affecting the Clogging of Recharge Wells in Different Soil ...
IRJET- Parameters Affecting the Clogging of Recharge Wells in Different Soil ...IRJET- Parameters Affecting the Clogging of Recharge Wells in Different Soil ...
IRJET- Parameters Affecting the Clogging of Recharge Wells in Different Soil ...IRJET Journal
 
Presentation on hydraulic conductivity and drainable porosity
Presentation on hydraulic conductivity and drainable porosityPresentation on hydraulic conductivity and drainable porosity
Presentation on hydraulic conductivity and drainable porosityAkhila Shiney
 
Assessment of siltation processes& implementation of nautical depth
Assessment of siltation processes& implementation of nautical depthAssessment of siltation processes& implementation of nautical depth
Assessment of siltation processes& implementation of nautical depthFaustino (Tino) Manso PhD MBA
 
Deep Marine Gas Hydrates; An Answer to India's Growing Energy Requirements?
Deep Marine Gas Hydrates; An Answer to India's Growing Energy Requirements?Deep Marine Gas Hydrates; An Answer to India's Growing Energy Requirements?
Deep Marine Gas Hydrates; An Answer to India's Growing Energy Requirements?IHS Markit
 
The strategy of hydrocarbon prediction (DHI) in deepwater exploration area-Ji...
The strategy of hydrocarbon prediction (DHI) in deepwater exploration area-Ji...The strategy of hydrocarbon prediction (DHI) in deepwater exploration area-Ji...
The strategy of hydrocarbon prediction (DHI) in deepwater exploration area-Ji...Abra(Jianli) Yang
 
Spe 163367-ms-p Modelling of regional aquifer.....Burgan Field Minagish Reser...
Spe 163367-ms-p Modelling of regional aquifer.....Burgan Field Minagish Reser...Spe 163367-ms-p Modelling of regional aquifer.....Burgan Field Minagish Reser...
Spe 163367-ms-p Modelling of regional aquifer.....Burgan Field Minagish Reser...Stephen Crittenden
 

What's hot (20)

Geotechnical Engineering-I [Lec #8: Hydrometer Analysis]
Geotechnical Engineering-I [Lec #8: Hydrometer Analysis]Geotechnical Engineering-I [Lec #8: Hydrometer Analysis]
Geotechnical Engineering-I [Lec #8: Hydrometer Analysis]
 
Study Results: Delineating Injection Well Buffer Zones in Brackish Aquifers
Study Results: Delineating Injection Well Buffer Zones in Brackish AquifersStudy Results: Delineating Injection Well Buffer Zones in Brackish Aquifers
Study Results: Delineating Injection Well Buffer Zones in Brackish Aquifers
 
IRJET- Open Channel Flow Characteristics using Gabion Weir
IRJET- Open Channel Flow Characteristics using Gabion WeirIRJET- Open Channel Flow Characteristics using Gabion Weir
IRJET- Open Channel Flow Characteristics using Gabion Weir
 
Potential impacts of CO2 storage on groundwater resources
Potential impacts of CO2 storage on groundwater resourcesPotential impacts of CO2 storage on groundwater resources
Potential impacts of CO2 storage on groundwater resources
 
Exploration for unconventional gas in russia
Exploration for unconventional gas in russiaExploration for unconventional gas in russia
Exploration for unconventional gas in russia
 
epa600-s-96-001
epa600-s-96-001epa600-s-96-001
epa600-s-96-001
 
Bodem Breed 2011 - Potential of Aquifer Storage and Recovery (ASR) for a clim...
Bodem Breed 2011 - Potential of Aquifer Storage and Recovery (ASR) for a clim...Bodem Breed 2011 - Potential of Aquifer Storage and Recovery (ASR) for a clim...
Bodem Breed 2011 - Potential of Aquifer Storage and Recovery (ASR) for a clim...
 
Hydrodynamic Modeling of the Physical Dispersion of Radium-Enriched Barite Ai...
Hydrodynamic Modeling of the Physical Dispersion of Radium-Enriched Barite Ai...Hydrodynamic Modeling of the Physical Dispersion of Radium-Enriched Barite Ai...
Hydrodynamic Modeling of the Physical Dispersion of Radium-Enriched Barite Ai...
 
Rationalizing the 1962-2006 Drop in Water Levels of Lakes Michigan and Huron
Rationalizing the 1962-2006 Drop in Water Levels of Lakes Michigan and HuronRationalizing the 1962-2006 Drop in Water Levels of Lakes Michigan and Huron
Rationalizing the 1962-2006 Drop in Water Levels of Lakes Michigan and Huron
 
WRE UNIT -V.pptx
WRE UNIT -V.pptxWRE UNIT -V.pptx
WRE UNIT -V.pptx
 
Petrophysical Properties of Reservoirs and Seal Characteristics at Ataga Oil ...
Petrophysical Properties of Reservoirs and Seal Characteristics at Ataga Oil ...Petrophysical Properties of Reservoirs and Seal Characteristics at Ataga Oil ...
Petrophysical Properties of Reservoirs and Seal Characteristics at Ataga Oil ...
 
IRJET- Parameters Affecting the Clogging of Recharge Wells in Different Soil ...
IRJET- Parameters Affecting the Clogging of Recharge Wells in Different Soil ...IRJET- Parameters Affecting the Clogging of Recharge Wells in Different Soil ...
IRJET- Parameters Affecting the Clogging of Recharge Wells in Different Soil ...
 
Resistivity Log
Resistivity LogResistivity Log
Resistivity Log
 
Presentation on hydraulic conductivity and drainable porosity
Presentation on hydraulic conductivity and drainable porosityPresentation on hydraulic conductivity and drainable porosity
Presentation on hydraulic conductivity and drainable porosity
 
Amarillo MLT_Hydrogeology 101_Ken Rainwater
Amarillo MLT_Hydrogeology 101_Ken RainwaterAmarillo MLT_Hydrogeology 101_Ken Rainwater
Amarillo MLT_Hydrogeology 101_Ken Rainwater
 
Beeville MLT_Groundwater 101_Marcus Gary
Beeville MLT_Groundwater 101_Marcus GaryBeeville MLT_Groundwater 101_Marcus Gary
Beeville MLT_Groundwater 101_Marcus Gary
 
Assessment of siltation processes& implementation of nautical depth
Assessment of siltation processes& implementation of nautical depthAssessment of siltation processes& implementation of nautical depth
Assessment of siltation processes& implementation of nautical depth
 
Deep Marine Gas Hydrates; An Answer to India's Growing Energy Requirements?
Deep Marine Gas Hydrates; An Answer to India's Growing Energy Requirements?Deep Marine Gas Hydrates; An Answer to India's Growing Energy Requirements?
Deep Marine Gas Hydrates; An Answer to India's Growing Energy Requirements?
 
The strategy of hydrocarbon prediction (DHI) in deepwater exploration area-Ji...
The strategy of hydrocarbon prediction (DHI) in deepwater exploration area-Ji...The strategy of hydrocarbon prediction (DHI) in deepwater exploration area-Ji...
The strategy of hydrocarbon prediction (DHI) in deepwater exploration area-Ji...
 
Spe 163367-ms-p Modelling of regional aquifer.....Burgan Field Minagish Reser...
Spe 163367-ms-p Modelling of regional aquifer.....Burgan Field Minagish Reser...Spe 163367-ms-p Modelling of regional aquifer.....Burgan Field Minagish Reser...
Spe 163367-ms-p Modelling of regional aquifer.....Burgan Field Minagish Reser...
 

Similar to OFFSHORE DEVELOPMENT PLAN

Effects of shale volume distribution on the elastic properties of reserviors ...
Effects of shale volume distribution on the elastic properties of reserviors ...Effects of shale volume distribution on the elastic properties of reserviors ...
Effects of shale volume distribution on the elastic properties of reserviors ...DR. RICHMOND IDEOZU
 
TGS GPS- Labrador Interpretation
TGS GPS- Labrador Interpretation TGS GPS- Labrador Interpretation
TGS GPS- Labrador Interpretation TGS
 
TGS GPS- Labrador Interpretation
TGS GPS- Labrador Interpretation TGS GPS- Labrador Interpretation
TGS GPS- Labrador Interpretation TGS
 
TGS GPS- DSDP Deepwater Borehole Data
TGS GPS-  DSDP Deepwater Borehole Data TGS GPS-  DSDP Deepwater Borehole Data
TGS GPS- DSDP Deepwater Borehole Data TGS
 
Reserve Estimation of Initial Oil and Gas by using Volumetric Method in Mann ...
Reserve Estimation of Initial Oil and Gas by using Volumetric Method in Mann ...Reserve Estimation of Initial Oil and Gas by using Volumetric Method in Mann ...
Reserve Estimation of Initial Oil and Gas by using Volumetric Method in Mann ...ijtsrd
 
Managing carbon geological storage and natural resources in sedimentary basins
Managing carbon geological storage and natural resources in sedimentary basinsManaging carbon geological storage and natural resources in sedimentary basins
Managing carbon geological storage and natural resources in sedimentary basinsGlobal CCS Institute
 
MSc thesis’2011
MSc thesis’2011MSc thesis’2011
MSc thesis’2011knyazevaig
 
Multidimensional analysis of data from Bari Harbour: a GIS based tool for the...
Multidimensional analysis of data from Bari Harbour: a GIS based tool for the...Multidimensional analysis of data from Bari Harbour: a GIS based tool for the...
Multidimensional analysis of data from Bari Harbour: a GIS based tool for the...SIGEA Puglia
 
Coures-Formation Evalution for petroleum Engineering -heriot watt university.pdf
Coures-Formation Evalution for petroleum Engineering -heriot watt university.pdfCoures-Formation Evalution for petroleum Engineering -heriot watt university.pdf
Coures-Formation Evalution for petroleum Engineering -heriot watt university.pdfAdnanAhmadJadoon
 
IRJET - Shrinkage Crack Study due to Lead Contamination in Bentonite Clay
IRJET - Shrinkage Crack Study due to Lead Contamination in Bentonite ClayIRJET - Shrinkage Crack Study due to Lead Contamination in Bentonite Clay
IRJET - Shrinkage Crack Study due to Lead Contamination in Bentonite ClayIRJET Journal
 
Cdw sed tank_tech_memo1111
Cdw sed tank_tech_memo1111Cdw sed tank_tech_memo1111
Cdw sed tank_tech_memo1111Mazen Alqadi
 
TGS NSA- East Coast Canada Labrador Sea
TGS NSA- East Coast Canada Labrador SeaTGS NSA- East Coast Canada Labrador Sea
TGS NSA- East Coast Canada Labrador SeaTGS
 
FSI-based Overflow Assessment of Liquid Storage Tanks
FSI-based Overflow Assessment of Liquid Storage TanksFSI-based Overflow Assessment of Liquid Storage Tanks
FSI-based Overflow Assessment of Liquid Storage TanksIRJET Journal
 
Delineation of Hydrocarbon Bearing Reservoirs from Surface Seismic and Well L...
Delineation of Hydrocarbon Bearing Reservoirs from Surface Seismic and Well L...Delineation of Hydrocarbon Bearing Reservoirs from Surface Seismic and Well L...
Delineation of Hydrocarbon Bearing Reservoirs from Surface Seismic and Well L...IOSR Journals
 

Similar to OFFSHORE DEVELOPMENT PLAN (20)

Sedimentation.ppt
Sedimentation.pptSedimentation.ppt
Sedimentation.ppt
 
Foundation Design of a Fixed Fuel Station (Case Study; Niger Delta Region of ...
Foundation Design of a Fixed Fuel Station (Case Study; Niger Delta Region of ...Foundation Design of a Fixed Fuel Station (Case Study; Niger Delta Region of ...
Foundation Design of a Fixed Fuel Station (Case Study; Niger Delta Region of ...
 
Effects of shale volume distribution on the elastic properties of reserviors ...
Effects of shale volume distribution on the elastic properties of reserviors ...Effects of shale volume distribution on the elastic properties of reserviors ...
Effects of shale volume distribution on the elastic properties of reserviors ...
 
TGS GPS- Labrador Interpretation
TGS GPS- Labrador Interpretation TGS GPS- Labrador Interpretation
TGS GPS- Labrador Interpretation
 
TGS GPS- Labrador Interpretation
TGS GPS- Labrador Interpretation TGS GPS- Labrador Interpretation
TGS GPS- Labrador Interpretation
 
TGS GPS- DSDP Deepwater Borehole Data
TGS GPS-  DSDP Deepwater Borehole Data TGS GPS-  DSDP Deepwater Borehole Data
TGS GPS- DSDP Deepwater Borehole Data
 
Reserve Estimation of Initial Oil and Gas by using Volumetric Method in Mann ...
Reserve Estimation of Initial Oil and Gas by using Volumetric Method in Mann ...Reserve Estimation of Initial Oil and Gas by using Volumetric Method in Mann ...
Reserve Estimation of Initial Oil and Gas by using Volumetric Method in Mann ...
 
SPE-178786-MS
SPE-178786-MSSPE-178786-MS
SPE-178786-MS
 
Managing carbon geological storage and natural resources in sedimentary basins
Managing carbon geological storage and natural resources in sedimentary basinsManaging carbon geological storage and natural resources in sedimentary basins
Managing carbon geological storage and natural resources in sedimentary basins
 
Spe 180818-ms
Spe 180818-msSpe 180818-ms
Spe 180818-ms
 
MSc thesis’2011
MSc thesis’2011MSc thesis’2011
MSc thesis’2011
 
Multidimensional analysis of data from Bari Harbour: a GIS based tool for the...
Multidimensional analysis of data from Bari Harbour: a GIS based tool for the...Multidimensional analysis of data from Bari Harbour: a GIS based tool for the...
Multidimensional analysis of data from Bari Harbour: a GIS based tool for the...
 
Coures-Formation Evalution for petroleum Engineering -heriot watt university.pdf
Coures-Formation Evalution for petroleum Engineering -heriot watt university.pdfCoures-Formation Evalution for petroleum Engineering -heriot watt university.pdf
Coures-Formation Evalution for petroleum Engineering -heriot watt university.pdf
 
IRJET - Shrinkage Crack Study due to Lead Contamination in Bentonite Clay
IRJET - Shrinkage Crack Study due to Lead Contamination in Bentonite ClayIRJET - Shrinkage Crack Study due to Lead Contamination in Bentonite Clay
IRJET - Shrinkage Crack Study due to Lead Contamination in Bentonite Clay
 
Cdw sed tank_tech_memo1111
Cdw sed tank_tech_memo1111Cdw sed tank_tech_memo1111
Cdw sed tank_tech_memo1111
 
Exploration Process Data
Exploration Process DataExploration Process Data
Exploration Process Data
 
IPTC-13174-ms
IPTC-13174-msIPTC-13174-ms
IPTC-13174-ms
 
TGS NSA- East Coast Canada Labrador Sea
TGS NSA- East Coast Canada Labrador SeaTGS NSA- East Coast Canada Labrador Sea
TGS NSA- East Coast Canada Labrador Sea
 
FSI-based Overflow Assessment of Liquid Storage Tanks
FSI-based Overflow Assessment of Liquid Storage TanksFSI-based Overflow Assessment of Liquid Storage Tanks
FSI-based Overflow Assessment of Liquid Storage Tanks
 
Delineation of Hydrocarbon Bearing Reservoirs from Surface Seismic and Well L...
Delineation of Hydrocarbon Bearing Reservoirs from Surface Seismic and Well L...Delineation of Hydrocarbon Bearing Reservoirs from Surface Seismic and Well L...
Delineation of Hydrocarbon Bearing Reservoirs from Surface Seismic and Well L...
 

More from ijtsrd

‘Six Sigma Technique’ A Journey Through its Implementation
‘Six Sigma Technique’ A Journey Through its Implementation‘Six Sigma Technique’ A Journey Through its Implementation
‘Six Sigma Technique’ A Journey Through its Implementationijtsrd
 
Edge Computing in Space Enhancing Data Processing and Communication for Space...
Edge Computing in Space Enhancing Data Processing and Communication for Space...Edge Computing in Space Enhancing Data Processing and Communication for Space...
Edge Computing in Space Enhancing Data Processing and Communication for Space...ijtsrd
 
Dynamics of Communal Politics in 21st Century India Challenges and Prospects
Dynamics of Communal Politics in 21st Century India Challenges and ProspectsDynamics of Communal Politics in 21st Century India Challenges and Prospects
Dynamics of Communal Politics in 21st Century India Challenges and Prospectsijtsrd
 
Assess Perspective and Knowledge of Healthcare Providers Towards Elehealth in...
Assess Perspective and Knowledge of Healthcare Providers Towards Elehealth in...Assess Perspective and Knowledge of Healthcare Providers Towards Elehealth in...
Assess Perspective and Knowledge of Healthcare Providers Towards Elehealth in...ijtsrd
 
The Impact of Digital Media on the Decentralization of Power and the Erosion ...
The Impact of Digital Media on the Decentralization of Power and the Erosion ...The Impact of Digital Media on the Decentralization of Power and the Erosion ...
The Impact of Digital Media on the Decentralization of Power and the Erosion ...ijtsrd
 
Online Voices, Offline Impact Ambedkars Ideals and Socio Political Inclusion ...
Online Voices, Offline Impact Ambedkars Ideals and Socio Political Inclusion ...Online Voices, Offline Impact Ambedkars Ideals and Socio Political Inclusion ...
Online Voices, Offline Impact Ambedkars Ideals and Socio Political Inclusion ...ijtsrd
 
Problems and Challenges of Agro Entreprenurship A Study
Problems and Challenges of Agro Entreprenurship A StudyProblems and Challenges of Agro Entreprenurship A Study
Problems and Challenges of Agro Entreprenurship A Studyijtsrd
 
Comparative Analysis of Total Corporate Disclosure of Selected IT Companies o...
Comparative Analysis of Total Corporate Disclosure of Selected IT Companies o...Comparative Analysis of Total Corporate Disclosure of Selected IT Companies o...
Comparative Analysis of Total Corporate Disclosure of Selected IT Companies o...ijtsrd
 
The Impact of Educational Background and Professional Training on Human Right...
The Impact of Educational Background and Professional Training on Human Right...The Impact of Educational Background and Professional Training on Human Right...
The Impact of Educational Background and Professional Training on Human Right...ijtsrd
 
A Study on the Effective Teaching Learning Process in English Curriculum at t...
A Study on the Effective Teaching Learning Process in English Curriculum at t...A Study on the Effective Teaching Learning Process in English Curriculum at t...
A Study on the Effective Teaching Learning Process in English Curriculum at t...ijtsrd
 
The Role of Mentoring and Its Influence on the Effectiveness of the Teaching ...
The Role of Mentoring and Its Influence on the Effectiveness of the Teaching ...The Role of Mentoring and Its Influence on the Effectiveness of the Teaching ...
The Role of Mentoring and Its Influence on the Effectiveness of the Teaching ...ijtsrd
 
Design Simulation and Hardware Construction of an Arduino Microcontroller Bas...
Design Simulation and Hardware Construction of an Arduino Microcontroller Bas...Design Simulation and Hardware Construction of an Arduino Microcontroller Bas...
Design Simulation and Hardware Construction of an Arduino Microcontroller Bas...ijtsrd
 
Sustainable Energy by Paul A. Adekunte | Matthew N. O. Sadiku | Janet O. Sadiku
Sustainable Energy by Paul A. Adekunte | Matthew N. O. Sadiku | Janet O. SadikuSustainable Energy by Paul A. Adekunte | Matthew N. O. Sadiku | Janet O. Sadiku
Sustainable Energy by Paul A. Adekunte | Matthew N. O. Sadiku | Janet O. Sadikuijtsrd
 
Concepts for Sudan Survey Act Implementations Executive Regulations and Stand...
Concepts for Sudan Survey Act Implementations Executive Regulations and Stand...Concepts for Sudan Survey Act Implementations Executive Regulations and Stand...
Concepts for Sudan Survey Act Implementations Executive Regulations and Stand...ijtsrd
 
Towards the Implementation of the Sudan Interpolated Geoid Model Khartoum Sta...
Towards the Implementation of the Sudan Interpolated Geoid Model Khartoum Sta...Towards the Implementation of the Sudan Interpolated Geoid Model Khartoum Sta...
Towards the Implementation of the Sudan Interpolated Geoid Model Khartoum Sta...ijtsrd
 
Activating Geospatial Information for Sudans Sustainable Investment Map
Activating Geospatial Information for Sudans Sustainable Investment MapActivating Geospatial Information for Sudans Sustainable Investment Map
Activating Geospatial Information for Sudans Sustainable Investment Mapijtsrd
 
Educational Unity Embracing Diversity for a Stronger Society
Educational Unity Embracing Diversity for a Stronger SocietyEducational Unity Embracing Diversity for a Stronger Society
Educational Unity Embracing Diversity for a Stronger Societyijtsrd
 
Integration of Indian Indigenous Knowledge System in Management Prospects and...
Integration of Indian Indigenous Knowledge System in Management Prospects and...Integration of Indian Indigenous Knowledge System in Management Prospects and...
Integration of Indian Indigenous Knowledge System in Management Prospects and...ijtsrd
 
DeepMask Transforming Face Mask Identification for Better Pandemic Control in...
DeepMask Transforming Face Mask Identification for Better Pandemic Control in...DeepMask Transforming Face Mask Identification for Better Pandemic Control in...
DeepMask Transforming Face Mask Identification for Better Pandemic Control in...ijtsrd
 
Streamlining Data Collection eCRF Design and Machine Learning
Streamlining Data Collection eCRF Design and Machine LearningStreamlining Data Collection eCRF Design and Machine Learning
Streamlining Data Collection eCRF Design and Machine Learningijtsrd
 

More from ijtsrd (20)

‘Six Sigma Technique’ A Journey Through its Implementation
‘Six Sigma Technique’ A Journey Through its Implementation‘Six Sigma Technique’ A Journey Through its Implementation
‘Six Sigma Technique’ A Journey Through its Implementation
 
Edge Computing in Space Enhancing Data Processing and Communication for Space...
Edge Computing in Space Enhancing Data Processing and Communication for Space...Edge Computing in Space Enhancing Data Processing and Communication for Space...
Edge Computing in Space Enhancing Data Processing and Communication for Space...
 
Dynamics of Communal Politics in 21st Century India Challenges and Prospects
Dynamics of Communal Politics in 21st Century India Challenges and ProspectsDynamics of Communal Politics in 21st Century India Challenges and Prospects
Dynamics of Communal Politics in 21st Century India Challenges and Prospects
 
Assess Perspective and Knowledge of Healthcare Providers Towards Elehealth in...
Assess Perspective and Knowledge of Healthcare Providers Towards Elehealth in...Assess Perspective and Knowledge of Healthcare Providers Towards Elehealth in...
Assess Perspective and Knowledge of Healthcare Providers Towards Elehealth in...
 
The Impact of Digital Media on the Decentralization of Power and the Erosion ...
The Impact of Digital Media on the Decentralization of Power and the Erosion ...The Impact of Digital Media on the Decentralization of Power and the Erosion ...
The Impact of Digital Media on the Decentralization of Power and the Erosion ...
 
Online Voices, Offline Impact Ambedkars Ideals and Socio Political Inclusion ...
Online Voices, Offline Impact Ambedkars Ideals and Socio Political Inclusion ...Online Voices, Offline Impact Ambedkars Ideals and Socio Political Inclusion ...
Online Voices, Offline Impact Ambedkars Ideals and Socio Political Inclusion ...
 
Problems and Challenges of Agro Entreprenurship A Study
Problems and Challenges of Agro Entreprenurship A StudyProblems and Challenges of Agro Entreprenurship A Study
Problems and Challenges of Agro Entreprenurship A Study
 
Comparative Analysis of Total Corporate Disclosure of Selected IT Companies o...
Comparative Analysis of Total Corporate Disclosure of Selected IT Companies o...Comparative Analysis of Total Corporate Disclosure of Selected IT Companies o...
Comparative Analysis of Total Corporate Disclosure of Selected IT Companies o...
 
The Impact of Educational Background and Professional Training on Human Right...
The Impact of Educational Background and Professional Training on Human Right...The Impact of Educational Background and Professional Training on Human Right...
The Impact of Educational Background and Professional Training on Human Right...
 
A Study on the Effective Teaching Learning Process in English Curriculum at t...
A Study on the Effective Teaching Learning Process in English Curriculum at t...A Study on the Effective Teaching Learning Process in English Curriculum at t...
A Study on the Effective Teaching Learning Process in English Curriculum at t...
 
The Role of Mentoring and Its Influence on the Effectiveness of the Teaching ...
The Role of Mentoring and Its Influence on the Effectiveness of the Teaching ...The Role of Mentoring and Its Influence on the Effectiveness of the Teaching ...
The Role of Mentoring and Its Influence on the Effectiveness of the Teaching ...
 
Design Simulation and Hardware Construction of an Arduino Microcontroller Bas...
Design Simulation and Hardware Construction of an Arduino Microcontroller Bas...Design Simulation and Hardware Construction of an Arduino Microcontroller Bas...
Design Simulation and Hardware Construction of an Arduino Microcontroller Bas...
 
Sustainable Energy by Paul A. Adekunte | Matthew N. O. Sadiku | Janet O. Sadiku
Sustainable Energy by Paul A. Adekunte | Matthew N. O. Sadiku | Janet O. SadikuSustainable Energy by Paul A. Adekunte | Matthew N. O. Sadiku | Janet O. Sadiku
Sustainable Energy by Paul A. Adekunte | Matthew N. O. Sadiku | Janet O. Sadiku
 
Concepts for Sudan Survey Act Implementations Executive Regulations and Stand...
Concepts for Sudan Survey Act Implementations Executive Regulations and Stand...Concepts for Sudan Survey Act Implementations Executive Regulations and Stand...
Concepts for Sudan Survey Act Implementations Executive Regulations and Stand...
 
Towards the Implementation of the Sudan Interpolated Geoid Model Khartoum Sta...
Towards the Implementation of the Sudan Interpolated Geoid Model Khartoum Sta...Towards the Implementation of the Sudan Interpolated Geoid Model Khartoum Sta...
Towards the Implementation of the Sudan Interpolated Geoid Model Khartoum Sta...
 
Activating Geospatial Information for Sudans Sustainable Investment Map
Activating Geospatial Information for Sudans Sustainable Investment MapActivating Geospatial Information for Sudans Sustainable Investment Map
Activating Geospatial Information for Sudans Sustainable Investment Map
 
Educational Unity Embracing Diversity for a Stronger Society
Educational Unity Embracing Diversity for a Stronger SocietyEducational Unity Embracing Diversity for a Stronger Society
Educational Unity Embracing Diversity for a Stronger Society
 
Integration of Indian Indigenous Knowledge System in Management Prospects and...
Integration of Indian Indigenous Knowledge System in Management Prospects and...Integration of Indian Indigenous Knowledge System in Management Prospects and...
Integration of Indian Indigenous Knowledge System in Management Prospects and...
 
DeepMask Transforming Face Mask Identification for Better Pandemic Control in...
DeepMask Transforming Face Mask Identification for Better Pandemic Control in...DeepMask Transforming Face Mask Identification for Better Pandemic Control in...
DeepMask Transforming Face Mask Identification for Better Pandemic Control in...
 
Streamlining Data Collection eCRF Design and Machine Learning
Streamlining Data Collection eCRF Design and Machine LearningStreamlining Data Collection eCRF Design and Machine Learning
Streamlining Data Collection eCRF Design and Machine Learning
 

Recently uploaded

Capitol Tech U Doctoral Presentation - April 2024.pptx
Capitol Tech U Doctoral Presentation - April 2024.pptxCapitol Tech U Doctoral Presentation - April 2024.pptx
Capitol Tech U Doctoral Presentation - April 2024.pptxCapitolTechU
 
MARGINALIZATION (Different learners in Marginalized Group
MARGINALIZATION (Different learners in Marginalized GroupMARGINALIZATION (Different learners in Marginalized Group
MARGINALIZATION (Different learners in Marginalized GroupJonathanParaisoCruz
 
POINT- BIOCHEMISTRY SEM 2 ENZYMES UNIT 5.pptx
POINT- BIOCHEMISTRY SEM 2 ENZYMES UNIT 5.pptxPOINT- BIOCHEMISTRY SEM 2 ENZYMES UNIT 5.pptx
POINT- BIOCHEMISTRY SEM 2 ENZYMES UNIT 5.pptxSayali Powar
 
Full Stack Web Development Course for Beginners
Full Stack Web Development Course  for BeginnersFull Stack Web Development Course  for Beginners
Full Stack Web Development Course for BeginnersSabitha Banu
 
Biting mechanism of poisonous snakes.pdf
Biting mechanism of poisonous snakes.pdfBiting mechanism of poisonous snakes.pdf
Biting mechanism of poisonous snakes.pdfadityarao40181
 
CARE OF CHILD IN INCUBATOR..........pptx
CARE OF CHILD IN INCUBATOR..........pptxCARE OF CHILD IN INCUBATOR..........pptx
CARE OF CHILD IN INCUBATOR..........pptxGaneshChakor2
 
call girls in Kamla Market (DELHI) 🔝 >༒9953330565🔝 genuine Escort Service 🔝✔️✔️
call girls in Kamla Market (DELHI) 🔝 >༒9953330565🔝 genuine Escort Service 🔝✔️✔️call girls in Kamla Market (DELHI) 🔝 >༒9953330565🔝 genuine Escort Service 🔝✔️✔️
call girls in Kamla Market (DELHI) 🔝 >༒9953330565🔝 genuine Escort Service 🔝✔️✔️9953056974 Low Rate Call Girls In Saket, Delhi NCR
 
Employee wellbeing at the workplace.pptx
Employee wellbeing at the workplace.pptxEmployee wellbeing at the workplace.pptx
Employee wellbeing at the workplace.pptxNirmalaLoungPoorunde1
 
Introduction to AI in Higher Education_draft.pptx
Introduction to AI in Higher Education_draft.pptxIntroduction to AI in Higher Education_draft.pptx
Introduction to AI in Higher Education_draft.pptxpboyjonauth
 
Introduction to ArtificiaI Intelligence in Higher Education
Introduction to ArtificiaI Intelligence in Higher EducationIntroduction to ArtificiaI Intelligence in Higher Education
Introduction to ArtificiaI Intelligence in Higher Educationpboyjonauth
 
Earth Day Presentation wow hello nice great
Earth Day Presentation wow hello nice greatEarth Day Presentation wow hello nice great
Earth Day Presentation wow hello nice greatYousafMalik24
 
Enzyme, Pharmaceutical Aids, Miscellaneous Last Part of Chapter no 5th.pdf
Enzyme, Pharmaceutical Aids, Miscellaneous Last Part of Chapter no 5th.pdfEnzyme, Pharmaceutical Aids, Miscellaneous Last Part of Chapter no 5th.pdf
Enzyme, Pharmaceutical Aids, Miscellaneous Last Part of Chapter no 5th.pdfSumit Tiwari
 
How to Make a Pirate ship Primary Education.pptx
How to Make a Pirate ship Primary Education.pptxHow to Make a Pirate ship Primary Education.pptx
How to Make a Pirate ship Primary Education.pptxmanuelaromero2013
 
“Oh GOSH! Reflecting on Hackteria's Collaborative Practices in a Global Do-It...
“Oh GOSH! Reflecting on Hackteria's Collaborative Practices in a Global Do-It...“Oh GOSH! Reflecting on Hackteria's Collaborative Practices in a Global Do-It...
“Oh GOSH! Reflecting on Hackteria's Collaborative Practices in a Global Do-It...Marc Dusseiller Dusjagr
 
Painted Grey Ware.pptx, PGW Culture of India
Painted Grey Ware.pptx, PGW Culture of IndiaPainted Grey Ware.pptx, PGW Culture of India
Painted Grey Ware.pptx, PGW Culture of IndiaVirag Sontakke
 
Final demo Grade 9 for demo Plan dessert.pptx
Final demo Grade 9 for demo Plan dessert.pptxFinal demo Grade 9 for demo Plan dessert.pptx
Final demo Grade 9 for demo Plan dessert.pptxAvyJaneVismanos
 
Crayon Activity Handout For the Crayon A
Crayon Activity Handout For the Crayon ACrayon Activity Handout For the Crayon A
Crayon Activity Handout For the Crayon AUnboundStockton
 
Hierarchy of management that covers different levels of management
Hierarchy of management that covers different levels of managementHierarchy of management that covers different levels of management
Hierarchy of management that covers different levels of managementmkooblal
 

Recently uploaded (20)

Capitol Tech U Doctoral Presentation - April 2024.pptx
Capitol Tech U Doctoral Presentation - April 2024.pptxCapitol Tech U Doctoral Presentation - April 2024.pptx
Capitol Tech U Doctoral Presentation - April 2024.pptx
 
MARGINALIZATION (Different learners in Marginalized Group
MARGINALIZATION (Different learners in Marginalized GroupMARGINALIZATION (Different learners in Marginalized Group
MARGINALIZATION (Different learners in Marginalized Group
 
POINT- BIOCHEMISTRY SEM 2 ENZYMES UNIT 5.pptx
POINT- BIOCHEMISTRY SEM 2 ENZYMES UNIT 5.pptxPOINT- BIOCHEMISTRY SEM 2 ENZYMES UNIT 5.pptx
POINT- BIOCHEMISTRY SEM 2 ENZYMES UNIT 5.pptx
 
Full Stack Web Development Course for Beginners
Full Stack Web Development Course  for BeginnersFull Stack Web Development Course  for Beginners
Full Stack Web Development Course for Beginners
 
Biting mechanism of poisonous snakes.pdf
Biting mechanism of poisonous snakes.pdfBiting mechanism of poisonous snakes.pdf
Biting mechanism of poisonous snakes.pdf
 
Model Call Girl in Bikash Puri Delhi reach out to us at 🔝9953056974🔝
Model Call Girl in Bikash Puri  Delhi reach out to us at 🔝9953056974🔝Model Call Girl in Bikash Puri  Delhi reach out to us at 🔝9953056974🔝
Model Call Girl in Bikash Puri Delhi reach out to us at 🔝9953056974🔝
 
CARE OF CHILD IN INCUBATOR..........pptx
CARE OF CHILD IN INCUBATOR..........pptxCARE OF CHILD IN INCUBATOR..........pptx
CARE OF CHILD IN INCUBATOR..........pptx
 
call girls in Kamla Market (DELHI) 🔝 >༒9953330565🔝 genuine Escort Service 🔝✔️✔️
call girls in Kamla Market (DELHI) 🔝 >༒9953330565🔝 genuine Escort Service 🔝✔️✔️call girls in Kamla Market (DELHI) 🔝 >༒9953330565🔝 genuine Escort Service 🔝✔️✔️
call girls in Kamla Market (DELHI) 🔝 >༒9953330565🔝 genuine Escort Service 🔝✔️✔️
 
9953330565 Low Rate Call Girls In Rohini Delhi NCR
9953330565 Low Rate Call Girls In Rohini  Delhi NCR9953330565 Low Rate Call Girls In Rohini  Delhi NCR
9953330565 Low Rate Call Girls In Rohini Delhi NCR
 
Employee wellbeing at the workplace.pptx
Employee wellbeing at the workplace.pptxEmployee wellbeing at the workplace.pptx
Employee wellbeing at the workplace.pptx
 
Introduction to AI in Higher Education_draft.pptx
Introduction to AI in Higher Education_draft.pptxIntroduction to AI in Higher Education_draft.pptx
Introduction to AI in Higher Education_draft.pptx
 
Introduction to ArtificiaI Intelligence in Higher Education
Introduction to ArtificiaI Intelligence in Higher EducationIntroduction to ArtificiaI Intelligence in Higher Education
Introduction to ArtificiaI Intelligence in Higher Education
 
Earth Day Presentation wow hello nice great
Earth Day Presentation wow hello nice greatEarth Day Presentation wow hello nice great
Earth Day Presentation wow hello nice great
 
Enzyme, Pharmaceutical Aids, Miscellaneous Last Part of Chapter no 5th.pdf
Enzyme, Pharmaceutical Aids, Miscellaneous Last Part of Chapter no 5th.pdfEnzyme, Pharmaceutical Aids, Miscellaneous Last Part of Chapter no 5th.pdf
Enzyme, Pharmaceutical Aids, Miscellaneous Last Part of Chapter no 5th.pdf
 
How to Make a Pirate ship Primary Education.pptx
How to Make a Pirate ship Primary Education.pptxHow to Make a Pirate ship Primary Education.pptx
How to Make a Pirate ship Primary Education.pptx
 
“Oh GOSH! Reflecting on Hackteria's Collaborative Practices in a Global Do-It...
“Oh GOSH! Reflecting on Hackteria's Collaborative Practices in a Global Do-It...“Oh GOSH! Reflecting on Hackteria's Collaborative Practices in a Global Do-It...
“Oh GOSH! Reflecting on Hackteria's Collaborative Practices in a Global Do-It...
 
Painted Grey Ware.pptx, PGW Culture of India
Painted Grey Ware.pptx, PGW Culture of IndiaPainted Grey Ware.pptx, PGW Culture of India
Painted Grey Ware.pptx, PGW Culture of India
 
Final demo Grade 9 for demo Plan dessert.pptx
Final demo Grade 9 for demo Plan dessert.pptxFinal demo Grade 9 for demo Plan dessert.pptx
Final demo Grade 9 for demo Plan dessert.pptx
 
Crayon Activity Handout For the Crayon A
Crayon Activity Handout For the Crayon ACrayon Activity Handout For the Crayon A
Crayon Activity Handout For the Crayon A
 
Hierarchy of management that covers different levels of management
Hierarchy of management that covers different levels of managementHierarchy of management that covers different levels of management
Hierarchy of management that covers different levels of management
 

OFFSHORE DEVELOPMENT PLAN

  • 1. International Journal of Trend in Scientific Research and Development (IJTSRD) Volume 5 Issue 1, November-December 2020 Available Online: www.ijtsrd.com e-ISSN: 2456 – 6470 @ IJTSRD | Unique Paper ID – IJTSRD35908 | Volume – 5 | Issue – 1 | November-December 2020 Page 467 First Development Plan for a Small Offshore Field Alfitouri Ibrahim Jellah Oil & Gas Engineering Department, Bani Waleed University, Bani Walid, Libya ABSTRACT This work describes the proposed development program for the accumulations in the virtual Beta field located in Libya offshore. In 2018, the contractor informed the Management Committee about the Commercial discovery of Beta-field. This development plan has been prepared for submission to the Management for its consideration. After collecting all the available data; including geological data, reservoir data, drilling data, production data, economical data, and environmental data. The suitable assumption has been made. All the modules were built with suitable sensitivities. The important resultswerelaidoutwithsomerecommendations in each section. Due consideration is paid to the environmental impact and all the possible use is made of the existing infrastructure. KEYWORDS: Field, Development Plan; Discovery, Oil, Reservoir Management, Depletion How to cite this paper: Alfitouri Ibrahim Jellah "First Development Plan for a Small Offshore Field" Published in International Journal of Trend in Scientific Research and Development(ijtsrd), ISSN: 2456-6470, Volume-5 | Issue-1, December 2020, pp.467-478, URL: www.ijtsrd.com/papers/ijtsrd35908.pdf Copyright © 2020 by author(s) and International Journal ofTrendinScientific Research and Development Journal. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0) (http://creativecommons.org/licenses/by/4.0) INTRODUCTION Beta-field is located offshore Libya in a waterdepthof 150 m. The structure is defined as Horst and Graben fault system predominantly orienting in the East-West direction. The crest of this anticlinal structure is 2550 m TVD SS with an oil water contact at 3160.5 m TVD SS. The stratigraphy consists of an old red sandstone reservoir from the Devonian period andsealingshale atthe topfrom the Lower Cretaceous period. Between these two periods lies an unconformity due to continual erosion. This reservoir is highly fractured with low porosity and low matrix permeability. It is composed of fluvial sediments deposited from braided river with multi channels. The Petrophysical analysis of the various logs from Beta- field, show a massive column of shaly-sandstonereservoir with low N/G, high initial water saturations and low matrix porosities. The reservoir properties of the field sands are poor, with porosity ranging of 10-13% and permeability in ranges from 0.06 mD to 12 mD. The core based wettability analyses indicate that the reservoir sands are mixed to oil-wet. Beta-field contains about 605 MMSTB of oil and 216.6 BSCF of associated gas in place within the massive old red shaly-sandstone reservoir. The oil and gas that can be economically recovered are estimated to be 157 MMSTB and 63 BSCF, respectively. Due toits geologicalcomplexity and associated uncertainties, it has been planned to develop Beta-field in three phases. A. Problem Statement This study is to check the profitability of Beta field after the information had been received from the contactor about its commercial recovery. B. Study Objectives This study was conducted on Beta field in order to achieve the following objectives: Decide whether it is profitable development or not, what are reserves and the associated uncertainty. Figure 1 - Seismic Cross Section. The kind of development plan should be adopted. The way the uncertainty in the data should be handled. IJTSRD35908
  • 2. International Journal of Trend in Scientific Research and Development (IJTSRD) @ www.ijtsrd.com eISSN: 2456-6470 @ IJTSRD | Unique Paper ID – IJTSRD35908 | Volume – 5 | Issue – 1 | November-December 2020 Page 468 Field Description A. Structural Configuration Beta-field was formed as a result of several geological changes. Originally, there was an anticline, then a normal faults system was generated, over time these started to subside generating a Horst and Graben fault system which created the structural trap. Subsequently on the top of the reservoir, a stratigraphic trap was created by sealing shale (approximate 430 ft at the thickest point). The shale was deposited during the Low Cretaceous (140 MM years ago) and reservoir sandstone was deposited during the Devonian (416- 359 MM years ago) which showsan unconformity due to the missing geological timebetweenthetworocks.Thetop structure map shows 21 normal faults, see figure 1. B. Fracture Analysis Origin: The fractures were generated due to stress during the folding of the anticlinefollowedbythenormal faults system creating a Horst and Graben sequence, see Figure 2. Fracture Network: Open fractures create secondary Figure 2 - 3D Braided River with sedimentary logs. Ref W. Beta-9 porosity due to increase of void space, but are strongly dependent on the scale size theyareexamined.Incertain areas, on a small scale secondary porosity can increase total porosity up to a factor of 100%. However, on the reservoir scale it only increases around 1 % of the total porosity. Storage Capacity: Studying the matrixandpermeability relationship, the matrix has the storage capacity and the communicating fractures aid the permeability. This phenomenon has been clearly demonstrated by calculating the ratio between the permeability obtained from the well test(K wt) andthe permeability measured in the core (K cl). C. Reservoir Description GeologyThe braided riversystemconsistedofanetwork of small channels separated by sandy or braid bars. As there had been had a tropical desert climate and the weather was more arid with occasional heavy rains causing dramatically variations in channel depths, channel velocity and sediment loads. This climate cycle was repeated during 150 million years resulting in new channels with low or high energy. Figure 3 shows a 3D braided river with different sedimentary logs. Petro physics and Reservoir Fluids The available data for estimating the petro physical properties for include core data and wireline logs. Table 2,lists thespecificlogs used for the analysis of the petro physical properties. All the exploration wells were drilled vertically except well Beta-6. Wire line log data was available for all six Exploration/Appraisal wells while the core data was available from wells Beta-2,Beta-3andBeta-5.Thecores were depth matched to the logs to ensure proper well interpretation. Fluid contacts The oil-water contact (OWC) was determined from the logs by observing an average decrease of 4 ohms in resistivity within wells Beta-1, Beta-2 and Beta-3. From the log interpretation of these wells the OWC was clearlyestablishedat10450ft,10490 ft and 10510ft MDBRT. The variation in the OWC has been interpreted as a result of porosity anisotropy and varying transition zones between the oil and water leg and not due to compartmentalizationofthereservoir.By selecting the shallowest OWC of 10450 ft TVD BRT, a worst-case scenario wasconsidered.Thefreewaterlevel (FWL) could not be established from the logs due to the uncertainty in the transition zones. However, for the STOIIP calculations this uncertainty has been managed by creating three scenarios that account for the possible FWL’s. The worst case scenario would be if the FWL was Figure 3 – Top Structure Map with Highlighted “Known Area” right below the deepest known oil at 10360 ft TVD BRT, the most likely case would have been the OWC at 10450 ft TVD BRT and finally the best case scenario wouldhave been if the FWL was at the highest known water at 10652 ft TVD BRT. Porosity It was obtained by comparing porosities from the different porosity models available in Terrastation software package. After comparing these models, the ‘Porter model’ was selected as the most representative for porosity across the whole reservoir section. The porosity determined from the gamma ray and sonic logs using Porter model was compared to the manually calculated values from the logs and the stress corrected core porosity data, which showed good agreement between them. Water saturation was also determined using Terrastation software package. Again, various models were compared to determine the most representative model. The ‘Laminar model’ which uses the porosity, resistivity and V-shale from logs was then chosen as the most representative. Volume of shale was determined using Terrastation software package. The various models available were compared to determine the most representative model.
  • 3. International Journal of Trend in Scientific Research and Development (IJTSRD) @ www.ijtsrd.com eISSN: 2456-6470 @ IJTSRD | Unique Paper ID – IJTSRD35908 | Volume – 5 | Issue – 1 | November-December 2020 Page 469 The ‘Density-Sonic model’ which uses the Sonic and the Bulk Density logs was then chosen as the most representative for the V-Shale calculations in all the wells. Cut off sensitivity analysis was performed on the cut offs used for the water saturation, V-shale and porosity in Terrastation to determine its varying effect on the net pay thickness andselecttheoptimumvalueforeachwell. The optimum cut off selected was the one which had the least effect on the net pay thickness. The Cut offs were varied by 20%, 35% and 50%of the maximumvalueand from these an optimum cut off value for V-shale, water saturation and porosity were selected for each well. Porosity - Permeability Cross Plot was created for Well-Beta-5, which had the most data available. Reservoir FluidsThe initial drilling and testing programmes showed that Beta-field oil is compositionally homogeneous with similar API gravity. PVT Study Both surface and sub-surface fluid samples were collected in wells Beta-1, Beta-2, Beta-3andBeta-5 for testing purposes. Wellhead samples and the recombined samples were collected at surface. Thirteen Down hole/surface recombined samples have been collected andanalyzed for basic blackoilPVTproperties. The single-phase PCT sample from Beta-2 DST-7andthe wellhead sample from Beta-2 DST-8 are considered the most representative of the full field reservoir fluid properties. As might be expected from the discussions above, the PVT data also show homogeneity within the reservoir. Ignoring these unrepresentative samples, oil samples that are clearly representative of the main oil column show bubblepointpressuresrangingfrom1340- 1342 psi, bubble point GOR’s of 346-359 scf/stb, bubble point formation volume factors of 1.299 – 1.322 rb/stb, API gravities of 31.1-32.2º, and bubble point oil viscosities ranging from 0.83-0.86 cp. Wettability and Relative Permeability Limited number of special core analyses has been conducteddue the limited time to determine capillary pressures, wettability, oil/water relative permeability,andresidual oil saturation. After reaching the residual oil saturation by forced displacement, the cores were tested for spontaneous imbibition of oil followed by measurement of additional oil recovery by forced displacement. The ratio of spontaneously uptake of oil tothetotaldisplaced oil gives a wettability index to oil, OWI. The Amott- Harvey Wettability index was calculated using the two ratios as: WI = WWI-OWI. All the cores taken at different depths in Well Beta-5 show a mixed oil-wet reservoir. Initial water saturations from these cores range 8% to 23%. Residual oil saturations from these cores range from 22% to 41%. (Figure 4). However, there are some measurement issues with this low permeability plug, particularly in the measurement of oil permeabilities. Note that the end-point Oil relative permeability is unrealistically high (kro (Swi) >1); which is physically impossible. Hence the end point rel. perms were modified to representcorrectdataforsimulationstudies.The modified rel. perm is as shown in Figure 5. Further SCAL studies would be performed on therecoveredcoredintervals during Phase-I that is considered a valuable input before drawing any further conclusions. Hydrocarbons in Place A. Deterministic STOIIP Estimates The following scenarios have been created to try to quantify the impact of the uncertainty with the top structure map and the contours. Case 1 – this has been done by considering the known area highlighted in blue in figure 6, as the most likely P50 scenario. In this area; the contours were then condensed by about 100 m to give P90 scenario, and extended by the same range to create P10 scenario. Case 2 – the same three P90, P50 and P10 GRV’s that were calculated for the knownareahavebeen considered in this case but with the GRV of both the North and South Flanks added on to each value. The STOIIP estimates are highlighted in Table 4 below. B. Uncertainty in STOIIP Estimates The following is a list of the key uncertainties in the estimation of STOIIP, and the work already planned which will help to reduce these uncertainties. Uncertainty in GRV Estimation - are due to the uncertainty in seismic time picking of the Top and Base horizons, position of the main bounding fault, depth conversion of the time surfaces and Depth of the OWC. N/G Uncertainty - The reservoir distribution inafluvial dominated setting is always difficult to establish. However the well control within the field has helped in building a reservoir distribution model, which was confirmed by the results from additional exploration wells drilled in this area. Hydrocarbon Saturation - The uncertainties in the saturation estimates are mainly due to the mixed-oil wet nature of the reservoir. Well-5 Rel Perm - 2781.31 m (39.2 md) 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Sw (Fraction) Kro(Fraction) 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Krw(Fraction) Kro Krw Well-5 Rel Perm - 2752.45 m (15.2 md) 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Sw (Fraction) Kro(Fraction) 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Krw(Fraction) Kro Krw Figure 4 – Rel Perm Curves from SCAL experiments in Well Beta-5
  • 4. International Journal of Trend in Scientific Research and Development (IJTSRD) @ www.ijtsrd.com eISSN: 2456-6470 @ IJTSRD | Unique Paper ID – IJTSRD35908 | Volume – 5 | Issue – 1 | November-December 2020 Page 470 Well-5 Rel Perm - 3050 m (9 md) 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Sw (Fraction) Kro(Fraction) 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Krw(Fraction) Kro Krw Well-5 Rel Perm - 3050 m (9 md) 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Sw (Fraction) Kro(Fraction) 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Krw(Fraction) Kro Krw Figure 5 – Rel Perm & Modified Rel Perm Curves for the most Representative Sample. Well Performance A. Production Test Analysis A total of 14 drill stem tests were performed in Beta-field. In well Beta-1 DST-3 had a mechanical failure as well DST-2 &3 in well Beta-2. The maximum oil production rate of 7492 BOPD was observed in well Beta-2 (DST-5); interval 9794- 9884 ft MDBRT & 9906-9942 ft MDBRT. The well Beta-5 (DST-1); interval 9462-9823 ft MDBRT also flowed at an average rate of 7032 BOPD. All other wells flowed at a significantly lower rate. The production tests performed in three wellsBeta-1,Beta-2 and Beta-3, along various intervals were aimed to collect most representative well test data. However due to extreme heterogeneity along thereservoir,qualitywelltestdatacould not be acquired. Most of the production tests show an increase in FBHP during drawdown indicating changingskin due to well clean up. To cope up with this uncertainty all the well tests were screened and the most representative have been analysed. B. Corrosion The corrosion level in Beta-field is intermediate, see Table 5.Hence, the use of normal materials like C80, N80 and Cr13 would be quite justifiable. C. Wax and Asphaltenes Currently no specific data isavailable on the wax appearance temperature and the asphaltenes concentration of Beta-field crude oil. A detailed analysiswould be performed in Phase–I to highlight any possible issues arising due to presence of wax and asphaltenes. The Reservoir Model A. The Geological Model The geological modelling wasperformedmodellingdifferent types of wells and various properties and faults. The orthonormal system was used for selecting the origin and the Northing and Easting of the model. The top structure map shows a lateral extent in the X direction (Easting) of 9800 m and in Y direction (Northing) of about 7275 m. The model was then digitized from the top structure map to include the different contours, faults and boundaries. Reservoir Structure -The current model isbasedon21faults present in the top structure map which weremodelledusing zigzag faults. These faults were constructed using vertical pillars, which were incorporated by joiningthe midpointsof the fault polygons in order to minimize errors associated with verticalization. -400.0 -300.0 -200.0 -100.0 0.0 100.0 200.0 300.0 400.0 500.0 600.0 700.0 800.0 900.0 1000.0 1100.0 1200.0 1300.0 1400.0 1500.0 1600.0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 Time (years) CumNCF Y Energy Field Cum NCF [$2008] NPV Delay NPV Figure 6 – Illustrate NCF, NPV and they effect of delay on NPV B. Property Modelling Reservoir properties have been modelled from the data available from Terrastation as an input to Petrel. The up scaled log data and original well log data have shown good correlation for the basic property parameters. A mean value of 9% for porosity, 7md for permeability and 35% for average water saturation was obtained from both up scaled and well logs. The well tops were identified and the OWC was determined at 3160.5 m TVDSS. C. Simulation Models The static geological model was exported to ECLIPSE for initiation of dynamic simulation. The logs show a very low matrix permeability and porosity across thereservoirwhich is in good agreement with the core studies. The main objective for this full field model was to study the effects of fracture-matrix constraints, run sensitivities and optimize well positioning. A total of 4 producers and 2 injectors were considered for the development of Beta field while taking into account the various uncertainties. In all the wells modelled a mechanical skin factor of 5 was assumed as the best case scenario. D. Initialization The model has been initialised with an OWC of 10370 ft. TVDSS. A datum pressure of 7534.7 psia at a datum depth of 9677.6 ft has been considered for hydrostatic equilibration of liquids. The reference pressure of 7881 psia at OWC has been used for initialization of rock and water properties.
  • 5. International Journal of Trend in Scientific Research and Development (IJTSRD) @ www.ijtsrd.com eISSN: 2456-6470 @ IJTSRD | Unique Paper ID – IJTSRD35908 | Volume – 5 | Issue – 1 | November-December 2020 Page 471 E. Model Sensitivities Natural Depletion Model - A base case with no water leg was considered to see the effect of compaction without an aquifer support on the recovery factor. Initially two cases were run, with two producers followed by two additional producers. These wells were placed on the crestal and central location for ease of quality data gatheringand adequate stand-offfromearly water encroachments which proved to be optimum for the drainage of the reservoir. Aquifer Modelling -Theexistenceofaquiferhasalready been determined from well testanalysisbuttheextentof the aquifer is an uncertainty. To deal with this uncertainty and its effect on recovery a finite numerical aquifer was attached to the bottom of the reservoir. The aquifer extents consideredforthismodelwere153*50m in the X direction and 67*50 m in Y direction, extending to thrice the size of the reservoir. F. Main Sensitivities and Results – Before concluding many factors had to be assessed. Out of these a few important ones have been short listed and play an elementary role in determining the reserves and URF of the reservoir. The sensitivities here have beenclassifiedinto two main categories: 1. Factors affecting STOIIP: NTG: An increase in NTG increases the STOIIP while a decrease automatically decreases the same. Considering a NTG of 0.67 as our base case for matrix, two more values has been used to run sensitivities which were obtained from the petro physical data, see Table 6 Connate watersaturation:Fromtheanalysisoflogdata & SCAL data no fixed connate water saturation could be identified for Beta field. As a result a sensitivity has been carried out for analysing the effect of connate water saturation on the reserves, see Table 7 2. Factors affecting RF and Water cut: Fracture Permeability: This is one of the prime and important factors affecting the recovery andwatercutof a reservoir. Beta-field reservoir is very heterogeneous and has channel sandsshowingpermeabilityanisotropy. Also, the well test data indicate different effective permeability values at different tested intervals. The available literature depicts that fracture porosity and permeability are a function ofthe effective permeability. In order to see the effects of fracture permeability onthe reservoir different sensitivities were done, see Table 8. Relative Permeability: Yet another important sensitivity is the relative permeability tables governing the relative oil and water permeabilities at different water saturations. From the SCAL data 5 sets of relative permeability tables were obtained. From this data, the most representative table was chosen for the base case while the rest were incorporated for sensitivity study. For the results see Table 9 Faults: The top structure map and the seismic interpretation show the presence of many faults in the reservoir. It would be of prime importance to see the fluid flow across these faults thatwouldhelptoknowthe nature of faults and transportation path of fluids. This would help in the later development stage of the field and would help in justifying well placements. As a result sensitivities were carried out using different values for fault multipliers in order to see the effect on the RF & water cut keeping 0.5 as the base case, see Table 10. G. Recovery Mechanism Different recovery mechanisms have been carried out using the full field simulation model of the Beta field. Natural depletion with and without aquifer drive has been investigated using this model. The initial reservoir pressure is 7881 psig at OWC which is higher than the average bubble point pressure of 1340 psig. Hence, when producing above the bubble point pressure, natural depletion to delineate aquifer drive would be the most attractive and optimum option in the first couple of years. Simulation runs indicate that aquifer strength is a very important parameter for deciding the further development stages, if needed. H. Alternative Development Plans Considered Limited data has been acquired until date from the exploration and the appraisal wells drilled in Beta-field to decide on a development strategy for this complex field. Further quality data needs to be acquired in this field to reduce the current uncertainties. Hence completing the 6 exploration/appraisal wells and acquiring the necessary data was considered the first option to develop Beta-field. Management Plan A. Economic Considerations The Economic Environment Overview Beta-field location is in the Mid Libyan Coast in Sirt Basin. This region is generally considered to be likely a gas area and therefore infrastructure development has modelled this assumption. For the purpose of this economic consideration, the economic environment and economical strategies of Libya will be the basis for economic assumptions and economic feasibility analysis. B. Cash Flow Modelling To determine the long-term feasibility and profitability of this project, there is a need to model the cash flow of the project with a view of determining the base profitability values of the project. The following base assumptions have been made and the outcome of these assumptions forms the input parameters of base case cash flow model. Base Case Input Parameters Inflation - The base price inflation for the cash flow model is 2.5%. This is based on the forecasted Libyan inflation rate 2.5%. Oil and Gas Price - The base assumption for oil and gas price are shown below: OIL PRICE Oil price assumption in nominal terms is us $88.25/barrel in 2018, $72.13/barrel in 2019, $68.29/barrel in 2020, $64.61/barrel in 2011 escalating at 2.5% per annum from the beginning of 2022 onwards. GAS PRICE Gas prices are linked to oil prices with a lag of three months. the average annualised gas price in nominal terms is $10.42/mcf in 2018, $9.45/mcf in 2019, $8.63/mcf in 2020, $8.19/mcf in 2021, escalating at 2.5% per annum from the beginning of 2022 onwards A discount of 10% has been assumed based on the fact that the API of Beta Field (320).
  • 6. International Journal of Trend in Scientific Research and Development (IJTSRD) @ www.ijtsrd.com eISSN: 2456-6470 @ IJTSRD | Unique Paper ID – IJTSRD35908 | Volume – 5 | Issue – 1 | November-December 2020 Page 472 Production Profile - The base case production profile for this economic model is the result of the full field simulation model run on eclipse. However to determine the economic life of the field, a plot of the revenue and operating cost / expense with time was done and it was determinedthattheoperatingcost(2018realterms)will become higher than the revenue (2018realterms)inthe 23rd year. Opex and Tariff - The components oftheOperatingCost include; Annual lease cost for FPSO, Gas pipeline usage tariff and CO2 and NOx tax. The base assumption for the lease cost is based on the average of the FPSO lease cost for field with similar production rates and recoverable reserves. The tariff for the transport system used in the base case cash flow model is (NKr 2.0 – 2.2 per Mcf). The CO2 andNOx tax is also considered asanoperatingcostin this base case model. Capex - The Capex of a development project is dependent on the following factors: Location peculiarities(remoteness,waterdepthandavailabilityof infrastructure), Reservoir geology and complexity, fluid properties (viscosity, numberofphases,impurities).The following development approaches were considered: 1. Lease FPSO, lay 30 km gas pipeline to the existing transport system for gas transport, Rent drilling rig for drilling operations and oil sales Free on Board (FOB). 2. Build FPSO, lay 30 km gas pipeline to the existing transport system for gas transport, Rent drilling rig for drilling operations and oil sales Free on Board (FOB). 3. rig for drilling operations and oil sales Free on Board (FOB). 4. Build Semi Sub for production processing, FSU for storage and lay 30 km pipeline to the existing transport system for gas transport, Rent drilling rig for drilling operations and oil sales Free on Board (FOB). Tax - The base case considered for taxation is same as described in the economic environmentanalysissection. Discount Rate - The discountrateemployedforthebase case is based on the mostlikelycasediscountrate(10%). Base Case Cash Flow Model Maximum Capital Outlay (MCO)– Inthiscase,theMCO for the base case model is USD210.3 million. MCO is the minimum point on the cumulative cash flow and it indicates the maximum amount of money to be sourced external to the project if the project is to survive the investment phase. It should also be noted that it is not same as the maximum Capex. Capex – For this project will be USD518million.Capexis alsoa measure of investmentsizeandgivesanindication of the cost of creating a productive unit. In this case it does not end before production as investment continues even after production has started. Pay Back – the Payback for Beta-field base case is 2.5 years. The payback is a measure of how long before investments are recouped. Terminal Cash Surplus (TCS) – For the base case is USD1428 million. It is an indication of the profit to be made by the project beforetakingintoaccountthecostof capital and the risk elementsof theinvestment(discount rate). Profit to Investment Ratio (PIR) – For the base case is 6.7. Internal Rate of Return (IRR) – For the base case is 86.5%. NPV – The NPV for the base case is USD 705Million. The NPV calculated for the base case is based on 10% discount rate. NPVI - The NPVI for the base case is 3.5 and the MCO Index is 6.8. Development Plan Beta-field oil has no unusual or troublesome properties, especially for water flooding. Beta-field’s high initial reservoir pressure 7881 psig at OWC, low GOR 358SCF/STB and low bubble point pressure 1340 psig, means that pressure maintenance by water flood might not be very critical at initial stages for reasonable recovery levels.There is sufficient evidence for these fractures being cemented, close to the OWC and within the water leg asdiscussedinthe sections above. Beta-field would be developed in different phases. The three Phases of development would be as follows: A. Phase-I: Natural depletion with 2 producers for initial 4 years. B. Phase-II: Natural depletion and/or Water-Flooding with 3 additional producers and 3 injectors depending of success of Phase-I. C. Phase-III: Use of gas lift for increasing ultimaterecovery and economic water cut. Well Optimization From the production profiles and the simulation studies done, an estimate of well optimization was established. Differences in recovery factors along with increase of wells and increase in water cut were plotted in order to optimize the number of wells to be used for the development. A. Base Case Development Plan Initially in Phase I, a naturaldepletionmechanismwas adopted. Two deviated wells acting as producers were placed on the crest and drilled into the northern and the southern flanks. The reason for the same was the presence of vertical and high angular fractures in the reservoir which constitutethemainfluidflowpathways. Two sensitivities, with and without aquifer were modelled to see the effect on RF. Case 1 : 2 producers with NTG = 0.67,Faulttransmissibility = 0.5, Skin = 5, BHP = 1500 psia (well control), without aquifer and runtime of 25 years. See Table 12. Case 2 : 2 producers with NTG = 0.67,Faulttransmissibility = 0.5, Skin = 5, BHP = 1500 psia (well control), with aquifer and runtime of 25 years. See Table 13. Wells Drilling and Work over For Beta-Field development; it is recommended to use a second generation Semi-submersible so cost will be lower. It’s is capable of drilling in water depths of 1000 ft and can drill up to 25000 ft which is well within the expecteddrilling targets. The phased drillingprogrammeisplannedthrougha drill centre with six slots on the seabed having a spacing of 15m between them. The FPSO will be located in such a position to accommodateanyunplannedwork overswithout interrupting the production.
  • 7. International Journal of Trend in Scientific Research and Development (IJTSRD) @ www.ijtsrd.com eISSN: 2456-6470 @ IJTSRD | Unique Paper ID – IJTSRD35908 | Volume – 5 | Issue – 1 | November-December 2020 Page 473 A. Pore & Fracture Pressure Prediction It is assumed the formation above the reservoir is normally pressured with a pressure gradient of 0.453 psi/ft. An oil gradient of 0.35 psi/ft is expectedwithinthereservoir which is over pressured by 2300 psi. For the normally pressured zone; an overbalance of 150 psi will be maintained while for the reservoir section it has been decided to maintain an overbalance of 100 psi to minimize formation damage (figure 7). B. Deviation Design It has been planned to follow a deviated well path with an angle of 55° to intersect the maximum number of high angled / vertical fractures and the inter-bedding layers within the reservoir, while keeping the angle within the range of wire line services. See figure 8. Figure 7 - Pore Pressure Profile A Positive Displacement Motor onthe17-1/2”PDCsteerable motor assembly will be used to kick off at 6250 ft with a build up rate of 1.5° / 100 ft to have a 10° angle at the 13- 3/8th casing setting depth (6490 ft) with an azimuth of 180°. The initial 10° angle is to reduce the severity of the build angle in the subsequent hole section. At the kick offpointthe formation is consolidatedsandstonewhichisnotexpectedto be a troublesome formation. Most essentially, the 10° inclination would facilitate the 12-1/4” rotary steerable system in finding the high side of the hole. The 12-1/4” RSS will be used to build up to 55° at BUR of 2° / 100 ft drilled with an azimuth of 180° to a TD of around 9320 ft. The TD for the 12-1/4” section would dependonthe rate of pressure increase in the transition zone (shale section), which would be monitored using the MWD to indicate the over pressured zone. C. Litho logy The compositional logs were analysed carefully and the expected litho logy description was used in choosing the casing setting depths. D. Drilling Schedule Drilling objectives of Phase I: Establish the reservoir potential of Beta-field by entering the Southern & Northern Flanks. Core reservoir section Complete suite of open hole logs E. Drill bit Selection Spud Drilling (9890 ft MD BRT) – While drilling thissection a one-trip approach will be implemented using a 17 ½” / 36” hole-opener. Once the TD for this section is reached the boulder intervals would be wiped clean to check for ledgesandensurethattheconductoris run within <1° inclination. 26” Drilling (2663 ft MD BRT) - This interval will be drilled with a 26” Roller Cone drill bit studded with tungsten carbide insertcutters. This is consideredbased on the length of this hole section (1673 ft), the cost of this type of bit (lower) and no hole size constraints. The drill string is designed to accommodate a small offset angle as to facilitate scrapping action and increase the drilling rate in the softer formations 17-1/2” Drilling (6595 ft MD BRT) - This interval will be drilled with a 17-1/2” PDC steerable motor assembly (SMA). The PDC has been selected due to its extended drillinglife (no moving components)anditissuitablefor drilling in hard, non –sticky formations without bit balling. The SMA will be in a rotary mode until it drills vertically up to 6100ft. It will then be switched to its sliding mode withcontinuous mud circulation througha PDM driving the drillbit. Figure 8 – Deviated Well Profile 12-1/4” Drilling (8853 ft MD BRT) - This interval will be drilled with a PDC Rotary Steerable System. The PDC bit is selected to achieve longer drilled intervals, lowering the amount of trip time and reducing the chances of failure due to no moving components. It also gives proper hole cleaning benefits allowing rotation of the string while building up at 2°/100ft up towards 55°. 8-1/2” Drilling (12186 ft MD BRT) - This interval will again be drilled with a PDC Rotary Steerable System for the same reasons as discussed in the previous section. However, the most important selection criteria for RSS for this hole section was to allow flexibility in maintaining correct path and deviation to reach the target zone in the Southern Flank. F. Casing Design The current calculation for the burst and collapse loads are based on the fluid properties that are present in the reservoir (discussed in reservoirengineering)andthefuture possibility of gas lifting, see table 14. However if phasethree is delayed then a possible work over and a re-evaluation of the casing integrity would be expected.
  • 8. International Journal of Trend in Scientific Research and Development (IJTSRD) @ www.ijtsrd.com eISSN: 2456-6470 @ IJTSRD | Unique Paper ID – IJTSRD35908 | Volume – 5 | Issue – 1 | November-December 2020 Page 474 Run and Cement 30” Casing (984 ft MD BRT) - This procedure could have problems getting conductor to bottom due to bottom fill and/or boulders falling / protruding into the hole. The drill pipe stringer would help on reducing the pumping time with lower displacement volumes and no chance of packers becoming stuck. However, “bridging off” in the annulus space might be an issue as large compressive loads may cause the conductor to collapse. The Top of Cement (TOC) will be to the seabedbetweenthetemporaryguide base (TGB) and permanent guide base (PGB). An excess of 100% of the gauge hole annular volume is planned to ensure good returns to seabed since this is a major load bearing element in the wellhead system. Run and Cement 20” Casing (2658 ft MD BRT)- The 20” surface casing will be cemented using single stage method as low pump pressures are expected at this shallow depth. The TOC will be till seabed between the TGB and PGB since this casing cement bond willalsobea major load bearing element in the wellhead system. The casing setting depth has been chosen to have the casing shoe within the limestone section and ensure a good L.O.T for the 17 1/2” section. Run and Cement 13-3/8” Casing (6590 ft MD BRT) - The 13-3/8” intermediate casing will again be cemented usinga single staged cementing operation. The available data shows no lost circulation within this section. The TOC is planned 500 ft above the 13-3/8 casing shoe at 6068 ft. The TOC will be changed to isolatethezonesthat contain gas lostcirculation zones. The amountofcement required for a particular job wouldbeonlydependenton the drilling problems encountered while drilling the section. Run and Cement 9-5/8” Casing (8848 ft MD BRT) - The casing setting depth for this 9-5/8” production casing is in the shale region just before the over pressured reservoir is encountered.Thiswouldfacilitate change over to higher mud weights before entering the over pressured reservoir. From analysis of the mud logs a lost circulation zone is likely to be encountered in the limestone region around 7300 ft would alsobesealedoff behind the casing. The top of cement for this casing interval will be placed 500ft above the expected lost circulation zone using a two staged cementing method. G. Well Control The BOP stack will be installed after cementing the 20” surface casing. The further hole sections would be drilled with a 10 000 psi BOP in place. The rating of the BOP stack is chosen on the basis of a worst case scenario of gas filling the casing all the way to surface. This scenario gives the expected surface pressure of 6150 psi which even with a safety factor of 20% is covered by the BOP rating. Once the 10, 000psi BOP is latched on it will be pressure tested to its working pressure limit before drilling later hole sections. The 26” hole will be drilled without a riser to around 2658 ft TVD BRT. From the available data the risk of encountering shallow gas has been deemed to be ‘low’. However, shallow seismic data, tidal current data with respect to tidal position and possible gas cone degree size will have to be collected before this decision is finalised. If loses are seen while drilling the mud weightshouldfirst be cut back to stop losing excessive mud in the fractured formation. If heavy losses continue, which is expecteddueto fractures or faults being “re-activated”and/oropeningin the formation then heavy duty LCM pills should be added. H. Drilling Mud Design It has been intended to use seawater planned until placing the riser and BOP to minimise environmental impact. Then moving to a water based mud with KCl / polymer to drill down to the setting depth of the 9-5/8” casing, to avoid any instability problems. Losses are expected when drilling the 8-1/2” hole section within the fractured. From the past data in well Betta-2 a maximum mud loss of 49 bbl/hr had been documented. Even though the high loss rates were not encountered while drilling the previous wells in Beta-field, safety measures should be in place to deal with these situations. Casing and Completion Design 1. Completion design An openhole Subsea completion is plannedforthe newwells in Phase-I and II, as the reservoir is naturally fractured, well consolidated with a very low matrix porosity and permeability. The Subsea completion is designed to include all the necessary completion jewellery like TRSSSV, gas lift mandrels, telescopic joint, SSD, Hydraulic set permanent packer with seal receptacle, top and bottom no-go nipples and a wireline entry guide. The 4-1/2” completion string would be RIH as an integrated assembly to set the Hydraulic packer as deep as possible and to have the WEG just below the 9-5/8” casing shoe depth. This wouldleavea complete 8- 1/2” openhole section across the reservoir. This is planned to have the highest Kh and the maximum inflow area available for flow. Though the formation is quite consolidated, the tendency for sand production in the later life of this field after water breakthrough cannot be neglected. Due to lack of sieve analysis data, a detailed sand control design could not be achieved at this stage. The various Completion equipment are: Tubular: The tubing sizes considered for different sensitivities were 2-7/8”OD, 3-1/2” OD, 4” OD, 4-1/2” OD, 5” OD and 5-1/2” OD. The criterion used toselectthe optimum tubing size was based on the technical and economic considerations. A reservoir pressure of 5500psi with a FTHP of 1000 psi and a maximum expected skin of 15 with a variation in water cut from 0- 90% was considered the worst case scenario for this analysis. It can be seen from this analysis that increment in oil flow rate by increasing the tubing size from 4-1/2” to 5” is small as compared to the increment from 4” to 4-1/2” tubing. Down hole Safety Valve: A Tubing Retrievable Sub- Surface Safety control Valve (TRSSSV) which provides more advantages compared to the Wire line Retrievable Safety Valve will be used. A TRSSVismorereliableasthis leaves less chance of control system leaks, permits a full bore passage and reduces wire line interventions. A flapper-type valve will also be required for a temporary lock-out. Production packer: A 9-5/8” hydraulic set permanent packer with seal receptacles will be used. This packer will be run on the completion tubing. Gas lift Mandrels: 3 x4-1/2” gas lift mandrels would be run along with the planned completion for future possible gas lifting operations.
  • 9. International Journal of Trend in Scientific Research and Development (IJTSRD) @ www.ijtsrd.com eISSN: 2456-6470 @ IJTSRD | Unique Paper ID – IJTSRD35908 | Volume – 5 | Issue – 1 | November-December 2020 Page 475 SSD: A sliding side door is included in the completionfor well killing operations for any possible workovers. Telescopic Joint: This equipment isrequiredasapartof the tubing to accommodate any expansion that will take place during production. Wire line entry guide: is used for smooth wire line interventions without any hung-up. Swell packer: This is a special type of packer which is used as an open hole plug to reduce the water cut. This will be required to plug off the watered out open hole sections in future. Tubing Hanger: The type of tubing hanger used is the hydraulic type which provided the facilities for tubing hanger setting and simultaneous wire line access to the bore. Subsea Xmas Tree: The production from the well required a Xmas Tree with a 4-inch nominal bore. The main valve assembly comprises of lower manual master valve, upper master valve, hydraulic wing valve and swab valve. These valves are fixed on the downstream side then connected to theflowloop.Thepressurerateof the wellhead equipment is 10000 psi. Production Facilities The potential production facilities available for the development include: A. Floating Production, Storage Facility From the economic and technical benefits,a FPSOunitwould be leased for this development. This unit which has a mono hull construction type will be considered becauseitwill host all the necessary facilities including the production, processing, storage and export. The FPSO will be placed between the glory holes and will receive productionvia flow lines through the turret located near the bow of the vessel. B. Surface Facilities for Production and Storage Vessel - The FPSO will have a design life of 25 years with a storage capacity of roughly 500000 barrels representing about 7 to 9 days of production. The peak liquid production to be handled by this FPSO will be 45000 barrels of oil per day and 13000 barrels of water per day. Test Separator - will be used for carrying out periodic well test to collect reservoir data. Multi-Stage Separator - The first stage separator (HP separator) will provide the initial stage of the crude oil separation. The incoming production fluids will be heated and allowed to settle in the HP separator. Crude from the first separator will be further separated in the LP separator and then in the electrostatic treater. Here remaining gas and water will be removed from the oil. The sales quality oil thus produced will then flow to the cargo tanks for storage until offloading. Water that has been separated from the oil will be processed to remove dissolved gasses. Gas Compressors -SeparatedgasfromtheHPseparator will be compressed to high pressure to allow it to be injected at the subsea wellhead soastofacilitatetheflow of the incoming production fluids(gaslift)laterinthelife of the field. Water Treatment - The produced water will then be treated to meet a maximum concentration of 30mg/l of oil-in-water specification before it can be disposed overboard. Utility Systems – Three main utility services will be needed – heating,coolingandelectricity.Theheatingand cooling will be providedbytheamedium,whichcontains circulating hot fresh water for process heating and cold fresh water for process and compressor cooling. The heating for the hot water system will be achieved using steam from the vessel’s boilers, and cooling for the cold water system will be achieved by using seawater. Seawater lift and injection system - During Phase-II, sea water will be required for injectionintothereservoir for pressure maintenance. Thus, three lift pumps and coarse filters will be required to treattheseawatertothe reservoir filtration requirements. De-aeration of the seawater will also be carried out prior to injection to prevent corrosion in the injection well. Gas Generators - Three Gas generators will provide electric power for the FPSO. Under normal conditions, two of the three topsides High Voltage (HV) generators will be on line. These will supply all topsides and vessel consumers. Flare and Vent System - There will be no continuous flaring except during emergency conditions. Measures will be evaluated to reduce atmospheric emission wherever possible. Safety Equipment - The vessel will be provided with a minimum of 150 percent capacity in persons onboardin lifeboats and 200 percent capacity in life rafts. Lifeboats and life rafts will be located close to the temporary refuge and on both sides of the vessel. Additional lifeboat(s) and life rafts will beprovidedatothersuitable locations on the vessel. All safety equipment will meet international marine requirements. Accommodation - The FPSO will provide accommodation for about 50 to 60 people located furthest away from the skids containing oil and gas. Crude Oil Metering - The crude oil product will be metered to custody transfer standards before offloading to the off-take tankers. Quantity and quality measurement of the liquid will be required to satisfy the DTI legal requirements for accounting and reporting purposes Export Gas Metering - Prior to being exported to the transportation system, dry associated gas will be metered by an orifice plate meter to the fiscal standard. Also, the quality of the gas will be compatible with the dense phase flowing criteria. Injection - Venturi flow meters will be installed on the Xmas tree to monitor the injection volumes. C. Subsea Production and Associated Facilities Subsea trees and controls - Subsea Christmas trees employed shall either be of vertical or horizontal Christmas tree and these will be using the manufacturers’ specifications. It will have the capability for production with gas lift and water injection. Subsea manifolds modules - Manifold modules will be required to handle flow from the producing wells and direct them into the production flow line headers, pigging loops, flow meters and control systems. Subsea manifolds will also be required for Phase-II of this development plan. This will provide for the functions of water injection and control. Subsea control systems and umbilicals - The Subsea control system is expected to be an open loop system that is powered electro -hydraulically. The FPSO located control equipment will be connected to the subsea
  • 10. International Journal of Trend in Scientific Research and Development (IJTSRD) @ www.ijtsrd.com eISSN: 2456-6470 @ IJTSRD | Unique Paper ID – IJTSRD35908 | Volume – 5 | Issue – 1 | November-December 2020 Page 476 equipment (e.g. manifold) via electro-hydraulic control umbilicals. Dynamic umbilicals will be used for control from a FPSO. The control system will be designed to supply sufficient hydraulic fluid high pressure (HP) and low pressure (LP) to control the remotely operated valves on the manifolds and Christmas trees at all drill centers. Consideration will also be given to possible future expansion requirements. Subsea flow lines and risers - The flow lines and risers for Beta-field will be designed to the APIstandards.They will provide an unobstructed flow conduit between the subsea facilities and the FPSO and will be fully compatible with the intended service for the entire design life. Valves will be installed to control flows for both normal and emergencysituations. Design wise, it is expected that no maintenance will be required during the design life, except for external inspection using an ROV and damage repair and operational pigging. D. Production Export Systems Offloading facilities - The FPSO will be designed such that the offloading facilities will be located at the sternof the vessel. A fiscal metering system will be incorporated as an integrated package. Oil export - Crude oil will be exported directly from the FPSO to the shuttle tanker. The shuttle tanker will be expected to be in the size range of 80,000 DWT. The cargo storage capacity is expected to be around 480,000 bbls to meet peak productionstorageperiodofupto8-10 days. Gas Export -Process gas export will be achieved via a nominal 6” diameter pipeline from the FPSO to the 42” Transport pipeline. This pipeline will be expected to be about 30km in length and will be trenched. The Transport pipeline will run some 730km to the landfall site at Karsto. Environmental Impact A. Existing Environment The measured sensitivities of the area are described below. 1. Any of this area has not been designated as a Special Areas of Conservation (SAC)ora Special ProtectionArea (SPC). The bottom sediment within this area is mainly mud and sand. 2. Seabirds are present throughout the year in this area except in April, September and December. 3. The fishing effort is classified as relatively low in this part of Libyan water. B. Risks and modification plans Modification plans have been developed for some activities which may cause environment impacts. The measured environmental impacts are described below: 1. High or low frequency sound emit into the marine environment during anchoring the drillingrigandwhile drilling. 2. The emissions raised from the drilling and production operations mainly from burning of well oil and gas during the short term of drill stream test and diesel combustion for power generation. 3. Oil spills and leaks may occur during various stages of the field development activities. 4. The seabed would directly be disturbed from the placement and the subsequent dragging of rig anchors. But, the physical presence of anchors is expected to create minor environmental impact on the benthos, which should recover quickly once operations are completed. 5. The cuttings contaminated from oil will be contained and shipped to shore for reprocessing at a licensed site. Abandonment A. General The current economicproductionfromBeta-fieldisexpected to last 25 years. However, this might extend depending on the success of Phase-II and Phase-III. Decommissioning of the wells and facilities will be in accordance with the legal requirements on the disposal of disused offshore installation. B. Subsea facilities It is planned that even though the sizes of all sub-sea pipelines are less than 10”, all those lines in trenching and burial will be flushed,pluggedanddecommissionedin-place. C. Wells To achieve effective isolation of the reservoir; all wells will be plugged and abandoned with two permanent barriers from the seabed and casing string will be recovered. D. FPSO The leased FPSO of Beta-field will be disconnected from the risers and collected by the leasing company. Any residual hazardous waste arising from this will be taken to shoreand treated at appropriate approved waste treatment facilities. Costs A. General The cost implications for this development plan have been divided into 2 broad aspects. 1. Capital Expenditure (Capex) 2. Operating Expenditure A breakdown of the revenue and the project costs including Opex, Capex and taxes is illustrated in figure 9. B. Exploration, Appraisal and Development Costs The key components of the Capex include the drilling, sub sea completion and the 30km pipeline from the FPSO to the transport system. There is no exploration and appraisal cost covered in this report as these cost have been considered as sunk cost. Due to the marginal nature of this field and the significant level of data uncertainty, the Capital expenditure will be phased into the three distinct phases. A pie chart that shows the phases and the magnitude of expense is shown below. C. Operating Expenditure (Opex) The Opex for this project can be considered high as this includes the cost of leasing the FPSO facility. Other components of the Opex include well maintenance, insurance logistics and consumables. Pipeline usage tariff is also included in the Opex. D. Abandonment Cost The abandonment cost for this project would cost $53.9 million in 2018 terms. This value comprises the cost of plugging the 4 producers and the 2 injectors. It will also include the cost of abandoning the pipelines. The FPSO
  • 11. International Journal of Trend in Scientific Research and Development (IJTSRD) @ www.ijtsrd.com eISSN: 2456-6470 @ IJTSRD | Unique Paper ID – IJTSRD35908 | Volume – 5 | Issue – 1 | November-December 2020 Page 477 lease contract will be terminated. The leasor will be responsible for its abandonment. Opex Capex Tax NCF Opex Capex Tax NCF Figure 9 – NCF as a proportion of the revenue. Abandonment Phase 3 Phase 2 Phase 1 Abandonment Phase 3 Phase 2 Phase 1 Figure 10 - Distribution of the Capex over the life of the project Operating personnel Logistics and consumables Inspection and maintenance Wells Insurance Tariff costs Lease Operating personnel Inspection and maintenance Logistics and consumables Wells Insurance Tariff costs Lease Figure 11 – Showing the distribution of the Opex over the life of the project References: [1] Reynolds D, (2006), 'High Performance Water Based drilling fluid helps achieve early oil withlowercapital expenditure' SPE 96798 [2] Svein Fantoft, (1992), 'Reservoir management of the Oseberg field After four years productionhistory'SPE 25008 [3] Morton K, (2006), ‘’Selection and Evaluation criteria for High Performance drilling fluids’' SPE 96342 [4] Chaudhry, A.U; (2004), “Oil Well Testing Handbook”; USA; Elsevier; [5] Jellah, A. I. et al., (2016), “Water Injection Performance Calculations in Intisar 103A Oil Field, Libya” , Paper presented at ICCPGE conference, Al- mergib University, Libya, , [6] Dye William et al, (2005), ‘New Water-Based Mud Balances High Performance Drilling and Environmental Compliance’ SPE 92367 [7] Dawber M et al, (2005), ‘Moving from Wire-line Logging to Logging-While-Drilling in an Aggressive North Sea Drilling and Formation Evaluation Program-A Case Study of the Brenda Accumulation’ SPE 96716 [8] Du K. E, Pai S. (2005), ‘Optimising the development of Blake field under tough economic and environmental conditions’ , SPE64714 [9] Blikra H, Andersen R, (2002), ‘Cost-effective Subsea drilling operation on the smallest Norwegian field development’ , SPE 74508 [10] Lanquentin B. ‘More Than 30 Years Experience with FPSO’s and offloading techniques’ 2005 IPTC 10901 [11] Stenger BA. (2006), ‘Extracting value from a dormant small offshore oil field: The Okwori Field Case’ , SPE 98875 [12] Maclean A. ‘Enhancing marginal Field Development economics by leasing operated production facilities. 2005 SPE 93507 [13] Stephen KD ‘Modelling and flow simulations of a north sea turbidite reservoir: Sensitivities and Upscaling’ 2002 SPE 78292 [14] Page Paul, Chris Greaves ‘Options for the recycling of drill cuttings’ 2003 SPE 80583 [15] Toole ST, Grist DM ‘Oil & Gas recovery behaviour in the UKCS basins’ 2003 SPE 83982 [16] Morton K., Bomar B, (2005), ‘Selectionand evaluation criteria for high-performance drilling fluids’ , SPE 96342. [17] . Holder Barry, J. et al, (1980 ), ‘Drilling Fluids for Highly Deviated Wells in North Sea Petroleum Drilling’ SPE 10860 [18] Hauge R et al, (2003), ‘Modeling Facies Bodies and Petro-physical Trents in Turbidite Reservoirs’ SPE 840 [19] Alyan, M., Martin, J., & Irwin, D. (2015, November 9). Field Development Plan Optimization for Tight Carbonate Reservoirs. Society of Petroleum Engineers. doi:10.2118/177695-MS [20] Safran, E. M., & Al Ansari, S. I. (2020, May 4). Flow Assurance Risks Impact on Kuwait Offshore Field Development Plans. Offshore TechnologyConference. doi:10.4043/30851-MS [21] Abdalla, O. S., Shawky, M., Badawy, O., Maarouf, M., & kamal, Y. (2015, September 14).ContinuesUpdatefor PetroSilah Full Fields Development Plan Results of Production and Reserves. Society of Petroleum Engineers. doi:10.2118/175807-MS [22] Teh, Y. H., Theseira, K., Abdul Karim, A. H., Hashim, N. S., Yakob, A. R., Musa, A. S., … Sykahar, M. W. (2008, January 1). Preparing a Gas Field Development Plan : Tangga Barat Cluster Gas Project. International Petroleum Technology Conference. doi:10.2523/IPTC-12488-MS [23] Ojeke, A., Itotoi, I. H., Nnamdi, D., Umurhohwo, J., & Benjamin, O. (2011, January 1). A Robust Approachto Field Development Plan Integrating Multi dynamic Reservoir Models with Surface Network. Society of Petroleum Engineers. doi:10.2118/150735-MS [24] Tahir, S., Al Kindi, S., Ghorayeb, K., Haryanto, E., Shah, A. R., Yersaiyn, S. … Ali, S. (2019, November11).ATop - Down View of Field Development Plans, Integrated
  • 12. International Journal of Trend in Scientific Research and Development (IJTSRD) @ www.ijtsrd.com eISSN: 2456-6470 @ IJTSRD | Unique Paper ID – IJTSRD35908 | Volume – 5 | Issue – 1 | November-December 2020 Page 478 Reservoir Performance and ProductionSustainability Assurance. Society of Petroleum Engineers. doi:10.2118/197379-MS [25] Sierra, F., Monge, A., Leon, S., Vasquez, F., Garcia, J., Llerena, G., & Borjas, J. (2015, November 18). A Real Case Study: Field Development Plan Evaluations for Oso Field. Society of Petroleum Engineers. doi:10.2118/177071-MS [26] Vilela, M. J., Marin, P. R., Rodrigo, M., Medina, A., Limeres, A. C., & Mata Petit, F. E. (2007, January 1). Building The Field Development Plan For A New Gas Field, Located In Algeria, Reggane Trend. Society of Petroleum Engineers. doi:10.2118/108831-MS [27] Denney, D. (2011, October 1). Offshore-Field Development Plan Changed From Steel Structures to Artificial Islands. Society of Petroleum Engineers. doi:10.2118/1011-0065-JPT [28] Kasap, E., Sanza, G. J., Ali, M. I., Friedel, T., Waheed, A., Sukmana, A. Y. … Rasol, M. N. (2006, January 1). Field Development Plan by Optioneering Process Sensitive to Reservoir and Operational Constraints and Uncertainties. Society of Petroleum Engineers. doi:10.2118/101556-MS